The version of Tencent Linux installed on the remote TencentOS Server 3 host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the TSSA-2022:0124 advisory.

    Package updates are available for TencentOS Server 3 that fix the following vulnerabilities:

    CVE-2019-12519:
    An issue was discovered in Squid through 4.7. When handling the tag esi:when when ESI is enabled, Squid     calls ESIExpression::Evaluate. This function uses a fixed stack buffer to hold the expression while it's     being evaluated. When processing the expression, it could either evaluate the top of the stack, or add a     new member to the stack. When adding a new member, there is no check to ensure that the stack won't     overflow.

    CVE-2019-12520:
    An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to     see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request.
    If found, it servers the request. The absolute URL can include the decoded UserInfo (username and     password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to     provide a username that has special characters to delimit the domain, and treat the rest of the URL as a     path or query string. An attacker could first make a request to their domain using an encoded username,     then when a request for the target domain comes in that decodes to the exact URL, it will serve the     attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows     an attacker to gain access to features that only reverse proxies can use, such as ESI.

    CVE-2019-12521:
    An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in     ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is     parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this     buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same     structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.

    CVE-2019-12523:
    An issue was discovered in Squid before 4.9. When handling a URN request, a corresponding HTTP request is     made. This HTTP request doesn't go through the access checks that incoming HTTP requests go through. This     causes all access checks to be bypassed and allows access to restricted HTTP servers, e.g., an attacker     can connect to HTTP servers that only listen on localhost.

    CVE-2019-12524:
    An issue was discovered in Squid through 4.7. When handling requests from users, Squid checks its rules to     see if the request should be denied. Squid by default comes with rules to block access to the Cache     Manager, which serves detailed server information meant for the maintainer. This rule is implemented via     url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to     encode their URL to bypass the url_regex check, and gain access to the blocked resource.

    CVE-2019-12525:
    An issue was discovered in Squid 3.3.9 through 3.5.28 and 4.x through 4.7. When Squid is configured to use     Digest authentication, it parses the header Proxy-Authorization. It searches for certain tokens such as     domain, uri, and qop. Squid checks if this token's value starts with a quote and ends with one. If so, it     performs a memcpy of its length minus 2. Squid never checks whether the value is just a single quote     (which would satisfy its requirements), leading to a memcpy of its length minus 1.

    CVE-2019-12526:
    An issue was discovered in Squid before 4.9. URN response handling in Squid suffers from a heap-based     buffer overflow. When receiving data from a remote server in response to an URN request, Squid fails to     ensure that the response can fit within the buffer. This leads to attacker controlled data overflowing in     the heap.

    CVE-2019-12527:
    An issue was discovered in Squid 4.0.23 through 4.7. When checking Basic Authentication with     HttpHeader::getAuth, Squid uses a global buffer to store the decoded data. Squid does not check that the     decoded length isn't greater than the buffer, leading to a heap-based buffer overflow with user controlled     data.

    CVE-2019-12528:
    An issue was discovered in Squid before 4.10. It allows a crafted FTP server to trigger disclosure of     sensitive information from heap memory, such as information associated with other users' sessions or non-     Squid processes.

    CVE-2019-12529:
    An issue was discovered in Squid 2.x through 2.7.STABLE9, 3.x through 3.5.28, and 4.x through 4.7. When     Squid is configured to use Basic Authentication, the Proxy-Authorization header is parsed via uudecode.
    uudecode determines how many bytes will be decoded by iterating over the input and checking its table. The     length is then used to start decoding the string. There are no checks to ensure that the length it     calculates isn't greater than the input buffer. This leads to adjacent memory being decoded as well. An     attacker would not be able to retrieve the decoded data unless the Squid maintainer had configured the     display of usernames on error pages.

    CVE-2019-12854:
    Due to incorrect string termination, Squid cachemgr.cgi 4.0 through 4.7 may access unallocated memory. On     systems with memory access protections, this can cause the CGI process to terminate unexpectedly,     resulting in a denial of service for all clients using it.

    CVE-2019-13345:
    The cachemgr.cgi web module of Squid through 4.7 has XSS via the user_name or auth parameter.

    CVE-2019-18676:
    An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a     heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. Severity     is high due to this vulnerability occurring before normal security checks; any remote client that can     reach the proxy port can trivially perform the attack via a crafted URI scheme.

    CVE-2019-18677:
    An issue was discovered in Squid 3.x and 4.x through 4.8 when the append_domain setting is used (because     the appended characters do not properly interact with hostname length restrictions). Due to incorrect     message processing, it can inappropriately redirect traffic to origins it should not be delivered to.

    CVE-2019-18678:
    An issue was discovered in Squid 3.x and 4.x through 4.8. It allows attackers to smuggle HTTP requests     through frontend software to a Squid instance that splits the HTTP Request pipeline differently. The     resulting Response messages corrupt caches (between a client and Squid) with attacker-controlled content     at arbitrary URLs. Effects are isolated to software between the attacker client and Squid. There are no     effects on Squid itself, nor on any upstream servers. The issue is related to a request header containing     whitespace between a header name and a colon.

    CVE-2019-18679:
    An issue was discovered in Squid 2.x, 3.x, and 4.x through 4.8. Due to incorrect data management, it is     vulnerable to information disclosure when processing HTTP Digest Authentication. Nonce tokens contain the     raw byte value of a pointer that sits within heap memory allocation. This information reduces ASLR     protections and may aid attackers isolating memory areas to target for remote code execution attacks.

    CVE-2019-18860:
    Squid before 4.9, when certain web browsers are used, mishandles HTML in the host (aka hostname) parameter     to cachemgr.cgi.

    CVE-2020-11945:
    An issue was discovered in Squid before 5.0.2. A remote attacker can replay a sniffed Digest     Authentication nonce to gain access to resources that are otherwise forbidden. This occurs because the     attacker can overflow the nonce reference counter (a short integer). Remote code execution may occur if     the pooled token credentials are freed (instead of replayed as valid credentials).

    CVE-2020-14058:
    An issue was discovered in Squid before 4.12 and 5.x before 5.0.3. Due to use of a potentially dangerous     function, Squid and the default certificate validation helper are vulnerable to a Denial of Service when     opening a TLS connection to an attacker-controlled server for HTTPS. This occurs because unrecognized     error values are mapped to NULL, but later code expects that each error value is mapped to a valid error     string.

    CVE-2020-15049:
    An issue was discovered in http/ContentLengthInterpreter.cc in Squid before 4.12 and 5.x before 5.0.3. A     Request Smuggling and Poisoning attack can succeed against the HTTP cache. The client sends an HTTP     request with a Content-Length header containing +\ - or an uncommon shell whitespace character prefix     to the length field-value.

    CVE-2020-15810:
    An issue was discovered in Squid before 4.13 and 5.x before 5.0.4. Due to incorrect data validation, HTTP     Request Smuggling attacks may succeed against HTTP and HTTPS traffic. This leads to cache poisoning. This     allows any client, including browser scripts, to bypass local security and poison the proxy cache and any     downstream caches with content from an arbitrary source. When configured for relaxed header parsing (the     default), Squid relays headers containing whitespace characters to upstream servers. When this occurs as a     prefix to a Content-Length header, the frame length specified will be ignored by Squid (allowing for a     conflicting length to be used from another Content-Length header) but relayed upstream.

    CVE-2020-15811:
    An issue was discovered in Squid before 4.13 and 5.x before 5.0.4. Due to incorrect data validation, HTTP     Request Splitting attacks may succeed against HTTP and HTTPS traffic. This leads to cache poisoning. This     allows any client, including browser scripts, to bypass local security and poison the browser cache and     any downstream caches with content from an arbitrary source. Squid uses a string search instead of parsing     the Transfer-Encoding header to find chunked encoding. This allows an attacker to hide a second request     inside Transfer-Encoding: it is interpreted by Squid as chunked and split out into a second request     delivered upstream. Squid will then deliver two distinct responses to the client, corrupting any     downstream caches.

    CVE-2020-24606:
    Squid before 4.13 and 5.x before 5.0.4 allows a trusted peer to perform Denial of Service by consuming all     available CPU cycles during handling of a crafted Cache Digest response message. This only occurs when     cache_peer is used with the cache digests feature. The problem exists because peerDigestHandleReply()     livelocking in peer_digest.cc mishandles EOF.

    CVE-2020-8449:
    An issue was discovered in Squid before 4.10. Due to incorrect input validation, it can interpret crafted     HTTP requests in unexpected ways to access server resources prohibited by earlier security filters.

    CVE-2020-8450:
    An issue was discovered in Squid before 4.10. Due to incorrect buffer management, a remote client can     cause a buffer overflow in a Squid instance acting as a reverse proxy.

Tenable has extracted the preceding description block directly from the Tencent Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Rocky Linux 8.6 host has packages installed that are affected by multiple vulnerabilities as referenced in the CIQ ciqsa-2026_0262 advisory.

    This advisory aggregates security fixes for the squid SRPM in CIQ LTS 8.6. It addresses 50 CVEs:
    CVE-2019-12520, CVE-2019-12524, CVE-2013-1839, CVE-2021-28116, CVE-2019-12529, and 45 more.

Tenable has extracted the preceding description block directly from the CIQ security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of squid installed on the remote host is prior to 3.5.20-17.45. It is, therefore, affected by a vulnerability as referenced in the ALAS-2023-1754 advisory.

    An issue was discovered in Squid before 4.12 and 5.x before 5.0.3. Due to use of a potentially dangerous     function, Squid and the default certificate validation helper are vulnerable to a Denial of Service when     opening a TLS connection to an attacker-controlled server for HTTPS. This occurs because unrecognized     error values are mapped to NULL, but later code expects that each error value is mapped to a valid error     string. (CVE-2020-14058)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Rocky Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RLSA-2020:4743 advisory.

  - An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to     see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request.
    If found, it servers the request. The absolute URL can include the decoded UserInfo (username and     password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to     provide a username that has special characters to delimit the domain, and treat the rest of the URL as a     path or query string. An attacker could first make a request to their domain using an encoded username,     then when a request for the target domain comes in that decodes to the exact URL, it will serve the     attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows     an attacker to gain access to features that only reverse proxies can use, such as ESI. (CVE-2019-12520)

  - An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in     ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is     parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this     buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same     structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.
    (CVE-2019-12521)

  - An issue was discovered in Squid before 4.9. When handling a URN request, a corresponding HTTP request is     made. This HTTP request doesn't go through the access checks that incoming HTTP requests go through. This     causes all access checks to be bypassed and allows access to restricted HTTP servers, e.g., an attacker     can connect to HTTP servers that only listen on localhost. (CVE-2019-12523)

  - An issue was discovered in Squid through 4.7. When handling requests from users, Squid checks its rules to     see if the request should be denied. Squid by default comes with rules to block access to the Cache     Manager, which serves detailed server information meant for the maintainer. This rule is implemented via     url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to     encode their URL to bypass the url_regex check, and gain access to the blocked resource. (CVE-2019-12524)

  - An issue was discovered in Squid before 4.9. URN response handling in Squid suffers from a heap-based     buffer overflow. When receiving data from a remote server in response to an URN request, Squid fails to     ensure that the response can fit within the buffer. This leads to attacker controlled data overflowing in     the heap. (CVE-2019-12526)

  - An issue was discovered in Squid before 4.10. It allows a crafted FTP server to trigger disclosure of     sensitive information from heap memory, such as information associated with other users' sessions or non-     Squid processes. (CVE-2019-12528)

  - An issue was discovered in Squid 2.x through 2.7.STABLE9, 3.x through 3.5.28, and 4.x through 4.7. When     Squid is configured to use Basic Authentication, the Proxy-Authorization header is parsed via uudecode.
    uudecode determines how many bytes will be decoded by iterating over the input and checking its table. The     length is then used to start decoding the string. There are no checks to ensure that the length it     calculates isn't greater than the input buffer. This leads to adjacent memory being decoded as well. An     attacker would not be able to retrieve the decoded data unless the Squid maintainer had configured the     display of usernames on error pages. (CVE-2019-12529)

  - Due to incorrect string termination, Squid cachemgr.cgi 4.0 through 4.7 may access unallocated memory. On     systems with memory access protections, this can cause the CGI process to terminate unexpectedly,     resulting in a denial of service for all clients using it. (CVE-2019-12854)

  - An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a     heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. Severity     is high due to this vulnerability occurring before normal security checks; any remote client that can     reach the proxy port can trivially perform the attack via a crafted URI scheme. (CVE-2019-18676)

  - An issue was discovered in Squid 3.x and 4.x through 4.8 when the append_domain setting is used (because     the appended characters do not properly interact with hostname length restrictions). Due to incorrect     message processing, it can inappropriately redirect traffic to origins it should not be delivered to.
    (CVE-2019-18677)

  - An issue was discovered in Squid 3.x and 4.x through 4.8. It allows attackers to smuggle HTTP requests     through frontend software to a Squid instance that splits the HTTP Request pipeline differently. The     resulting Response messages corrupt caches (between a client and Squid) with attacker-controlled content     at arbitrary URLs. Effects are isolated to software between the attacker client and Squid. There are no     effects on Squid itself, nor on any upstream servers. The issue is related to a request header containing     whitespace between a header name and a colon. (CVE-2019-18678)

  - An issue was discovered in Squid 2.x, 3.x, and 4.x through 4.8. Due to incorrect data management, it is     vulnerable to information disclosure when processing HTTP Digest Authentication. Nonce tokens contain the     raw byte value of a pointer that sits within heap memory allocation. This information reduces ASLR     protections and may aid attackers isolating memory areas to target for remote code execution attacks.
    (CVE-2019-18679)

  - Squid before 4.9, when certain web browsers are used, mishandles HTML in the host (aka hostname) parameter     to cachemgr.cgi. (CVE-2019-18860)

  - An issue was discovered in Squid before 4.12 and 5.x before 5.0.3. Due to use of a potentially dangerous     function, Squid and the default certificate validation helper are vulnerable to a Denial of Service when     opening a TLS connection to an attacker-controlled server for HTTPS. This occurs because unrecognized     error values are mapped to NULL, but later code expects that each error value is mapped to a valid error     string. (CVE-2020-14058)

  - An issue was discovered in http/ContentLengthInterpreter.cc in Squid before 4.12 and 5.x before 5.0.3. A     Request Smuggling and Poisoning attack can succeed against the HTTP cache. The client sends an HTTP     request with a Content-Length header containing +\ - or an uncommon shell whitespace character prefix     to the length field-value. (CVE-2020-15049)

  - Squid before 4.13 and 5.x before 5.0.4 allows a trusted peer to perform Denial of Service by consuming all     available CPU cycles during handling of a crafted Cache Digest response message. This only occurs when     cache_peer is used with the cache digests feature. The problem exists because peerDigestHandleReply()     livelocking in peer_digest.cc mishandles EOF. (CVE-2020-24606)

  - An issue was discovered in Squid before 4.10. Due to incorrect input validation, it can interpret crafted     HTTP requests in unexpected ways to access server resources prohibited by earlier security filters.
    (CVE-2020-8449)

  - An issue was discovered in Squid before 4.10. Due to incorrect buffer management, a remote client can     cause a buffer overflow in a Squid instance acting as a reverse proxy. (CVE-2020-8450)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - An issue was discovered in Squid before 4.12 and 5.x before 5.0.3. Due to use of a potentially dangerous     function, Squid and the default certificate validation helper are vulnerable to a Denial of Service when     opening a TLS connection to an attacker-controlled server for HTTPS. This occurs because unrecognized     error values are mapped to NULL, but later code expects that each error value is mapped to a valid error     string. (CVE-2020-14058)

Note that Nessus relies on the presence of the package as reported by the vendor.

According to its banner, the version of Squid running on the remote host is 2.x prior to 4.12 or 5.x prior to 5.0.3. It is,therefore, affected by multiple vulnerabilities:
  - Multiple denial of service (DoS) vulnerabilities exist in the SMP cache and TLS handshake implementations of Squid.   An unauthenticated, remote attacker can exploit these issues, by sending specially crafted requests to an affected   instance, to impose a DoS condition on the application (CVE-2020-14058, CVE-2020-14059). 

  - A cache poisoning vulnerability exists in Squid due to insufficient user input validation. An authenticated, remote   attacker can exploit this issue, to affect the integrity of the contents returned to users from the cache   (CVE-2020-15049).

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

According to the versions of the squid packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - An issue was discovered in Squid before 4.12 and 5.x     before 5.0.3. Due to use of a potentially dangerous     function, Squid and the default certificate validation     helper are vulnerable to a Denial of Service when     opening a TLS connection to an attacker-controlled     server for HTTPS. This occurs because unrecognized     error values are mapped to NULL, but later code expects     that each error value is mapped to a valid error     string.(CVE-2020-14058)

  - An issue was discovered in Squid through 4.13 and 5.x     through 5.0.4. Due to improper input validation, it     allows a trusted client to perform HTTP Request     Smuggling and access services otherwise forbidden by     the security controls. This occurs for certain     uri_whitespace configuration settings.(CVE-2020-25097)

  - An issue was discovered in Squid before 4.15 and 5.x     before 5.0.6. Due to an input-validation bug, it is     vulnerable to a Denial of Service attack (against all     clients using the proxy). A client sends an HTTP Range     request to trigger this.(CVE-2021-31808)

  - An issue was discovered in Squid before 4.15 and 5.x     before 5.0.6. Due to a buffer-management bug, it allows     a denial of service. When resolving a request with the     urn: scheme, the parser leaks a small amount of memory.
    However, there is an unspecified attack methodology     that can easily trigger a large amount of memory     consumption.(CVE-2021-28651)

  - An issue was discovered in Squid before 4.15 and 5.x     before 5.0.6. Due to a memory-management bug, it is     vulnerable to a Denial of Service attack (against all     clients using the proxy) via HTTP Range request     processing.(CVE-2021-31806)

  - Squid before 4.15 and 5.x before 5.0.6 allows remote     servers to cause a denial of service (affecting     availability to all clients) via an HTTP response. The     issue trigger is a header that can be expected to exist     in HTTP traffic without any malicious intent by the     server.(CVE-2021-33620)

  - An issue was discovered in Squid before 4.15 and 5.x     before 5.0.6. An integer overflow problem allows a     remote server to achieve Denial of Service when     delivering responses to HTTP Range requests. The issue     trigger is a header that can be expected to exist in     HTTP traffic without any malicious     intent.(CVE-2021-31807)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

According to the version of the squid package installed, the EulerOS installation on the remote host is affected by the following vulnerability :

  - An issue was discovered in Squid before 4.12 and 5.x     before 5.0.3. Due to use of a potentially dangerous     function, Squid and the default certificate validation     helper are vulnerable to a Denial of Service when     opening a TLS connection to an attacker-controlled     server for HTTPS. This occurs because unrecognized     error values are mapped to NULL, but later code expects     that each error value is mapped to a valid error     string.(CVE-2020-14058)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2020:4743 advisory.

    Squid is a high-performance proxy caching server for web clients, supporting FTP, Gopher, and HTTP data     objects.

    The following packages have been upgraded to a later upstream version: squid (4.11). (BZ#1829467)

    Security Fix(es):

    * squid: Improper input validation in request allows for proxy manipulation (CVE-2019-12520)

    * squid: Off-by-one error in addStackElement allows for heap buffer overflow and crash (CVE-2019-12521)

    * squid: Improper input validation in URI processor (CVE-2019-12523)

    * squid: Improper access restriction in url_regex may lead to security bypass (CVE-2019-12524)

    * squid: Heap overflow issue in URN processing (CVE-2019-12526)

    * squid: Information Disclosure issue in FTP Gateway (CVE-2019-12528)

    * squid: Out of bounds read in Proxy-Authorization header causes DoS (CVE-2019-12529)

    * squid: Denial of service in cachemgr.cgi (CVE-2019-12854)

    * squid: Buffer overflow in URI processor (CVE-2019-18676)

    * squid: Cross-Site Request Forgery issue in HTTP Request processing (CVE-2019-18677)

    * squid: HTTP Request Splitting issue in HTTP message processing (CVE-2019-18678)

    * squid: Information Disclosure issue in HTTP Digest Authentication (CVE-2019-18679)

    * squid: Mishandled HTML in the host parameter to cachemgr.cgi results in insecure behaviour     (CVE-2019-18860)

    * squid: Improper input validation issues in HTTP Request processing (CVE-2020-8449)

    * squid: Buffer overflow in reverse-proxy configurations (CVE-2020-8450)

    * squid: DoS in TLS handshake (CVE-2020-14058)

    * squid: Request smuggling and poisoning attack against the HTTP cache (CVE-2020-15049)

    * squid: Improper input validation could result in a DoS (CVE-2020-24606)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

    Additional Changes:

    For detailed information on changes in this release, see the Red Hat Enterprise Linux 8.3 Release Notes     linked from the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Alibaba Cloud Linux 3 host has packages installed that are affected by multiple vulnerabilities as referenced in the ALINUX3-SA-2022:0124 advisory.

    Package updates are available for Alibaba Cloud Linux 3 that fix the following vulnerabilities:

    CVE-2019-12519:
    An issue was discovered in Squid through 4.7. When handling the tag esi:when when ESI is enabled, Squid     calls ESIExpression::Evaluate. This function uses a fixed stack buffer to hold the expression while it's     being evaluated. When processing the expression, it could either evaluate the top of the stack, or add a     new member to the stack. When adding a new member, there is no check to ensure that the stack won't     overflow.

    CVE-2019-12520:
    An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to     see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request.
    If found, it servers the request. The absolute URL can include the decoded UserInfo (username and     password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to     provide a username that has special characters to delimit the domain, and treat the rest of the URL as a     path or query string. An attacker could first make a request to their domain using an encoded username,     then when a request for the target domain comes in that decodes to the exact URL, it will serve the     attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows     an attacker to gain access to features that only reverse proxies can use, such as ESI.

    CVE-2019-12521:
    An issue was discovered in Squid through 4.7. When Squid is parsing ESI, it keeps the ESI elements in     ESIContext. ESIContext contains a buffer for holding a stack of ESIElements. When a new ESIElement is     parsed, it is added via addStackElement. addStackElement has a check for the number of elements in this     buffer, but it's off by 1, leading to a Heap Overflow of 1 element. The overflow is within the same     structure so it can't affect adjacent memory blocks, and thus just leads to a crash while processing.

    CVE-2019-12523:
    An issue was discovered in Squid before 4.9. When handling a URN request, a corresponding HTTP request is     made. This HTTP request doesn't go through the access checks that incoming HTTP requests go through. This     causes all access checks to be bypassed and allows access to restricted HTTP servers, e.g., an attacker     can connect to HTTP servers that only listen on localhost.

    CVE-2019-12524:
    An issue was discovered in Squid through 4.7. When handling requests from users, Squid checks its rules to     see if the request should be denied. Squid by default comes with rules to block access to the Cache     Manager, which serves detailed server information meant for the maintainer. This rule is implemented via     url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to     encode their URL to bypass the url_regex check, and gain access to the blocked resource.

    CVE-2019-12525:
    An issue was discovered in Squid 3.3.9 through 3.5.28 and 4.x through 4.7. When Squid is configured to use     Digest authentication, it parses the header Proxy-Authorization. It searches for certain tokens such as     domain, uri, and qop. Squid checks if this token's value starts with a quote and ends with one. If so, it     performs a memcpy of its length minus 2. Squid never checks whether the value is just a single quote     (which would satisfy its requirements), leading to a memcpy of its length minus 1.

    CVE-2019-12526:
    An issue was discovered in Squid before 4.9. URN response handling in Squid suffers from a heap-based     buffer overflow. When receiving data from a remote server in response to an URN request, Squid fails to     ensure that the response can fit within the buffer. This leads to attacker controlled data overflowing in     the heap.

    CVE-2019-12527:
    An issue was discovered in Squid 4.0.23 through 4.7. When checking Basic Authentication with     HttpHeader::getAuth, Squid uses a global buffer to store the decoded data. Squid does not check that the     decoded length isn't greater than the buffer, leading to a heap-based buffer overflow with user controlled     data.

    CVE-2019-12528:
    An issue was discovered in Squid before 4.10. It allows a crafted FTP server to trigger disclosure of     sensitive information from heap memory, such as information associated with other users' sessions or non-     Squid processes.

    CVE-2019-12529:
    An issue was discovered in Squid 2.x through 2.7.STABLE9, 3.x through 3.5.28, and 4.x through 4.7. When     Squid is configured to use Basic Authentication, the Proxy-Authorization header is parsed via uudecode.
    uudecode determines how many bytes will be decoded by iterating over the input and checking its table. The     length is then used to start decoding the string. There are no checks to ensure that the length it     calculates isn't greater than the input buffer. This leads to adjacent memory being decoded as well. An     attacker would not be able to retrieve the decoded data unless the Squid maintainer had configured the     display of usernames on error pages.

    CVE-2019-12854:
    Due to incorrect string termination, Squid cachemgr.cgi 4.0 through 4.7 may access unallocated memory. On     systems with memory access protections, this can cause the CGI process to terminate unexpectedly,     resulting in a denial of service for all clients using it.

    CVE-2019-13345:
    The cachemgr.cgi web module of Squid through 4.7 has XSS via the user_name or auth parameter.

    CVE-2019-18676:
    An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a     heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. Severity     is high due to this vulnerability occurring before normal security checks; any remote client that can     reach the proxy port can trivially perform the attack via a crafted URI scheme.

    CVE-2019-18677:
    An issue was discovered in Squid 3.x and 4.x through 4.8 when the append_domain setting is used (because     the appended characters do not properly interact with hostname length restrictions). Due to incorrect     message processing, it can inappropriately redirect traffic to origins it should not be delivered to.

    CVE-2019-18678:
    An issue was discovered in Squid 3.x and 4.x through 4.8. It allows attackers to smuggle HTTP requests     through frontend software to a Squid instance that splits the HTTP Request pipeline differently. The     resulting Response messages corrupt caches (between a client and Squid) with attacker-controlled content     at arbitrary URLs. Effects are isolated to software between the attacker client and Squid. There are no     effects on Squid itself, nor on any upstream servers. The issue is related to a request header containing     whitespace between a header name and a colon.

    CVE-2019-18679:
    An issue was discovered in Squid 2.x, 3.x, and 4.x through 4.8. Due to incorrect data management, it is     vulnerable to information disclosure when processing HTTP Digest Authentication. Nonce tokens contain the     raw byte value of a pointer that sits within heap memory allocation. This information reduces ASLR     protections and may aid attackers isolating memory areas to target for remote code execution attacks.

    CVE-2019-18860:
    Squid before 4.9, when certain web browsers are used, mishandles HTML in the host (aka hostname) parameter     to cachemgr.cgi.

    CVE-2020-11945:
    An issue was discovered in Squid before 5.0.2. A remote attacker can replay a sniffed Digest     Authentication nonce to gain access to resources that are otherwise forbidden. This occurs because the     attacker can overflow the nonce reference counter (a short integer). Remote code execution may occur if     the pooled token credentials are freed (instead of replayed as valid credentials).

    CVE-2020-14058:
    An issue was discovered in Squid before 4.12 and 5.x before 5.0.3. Due to use of a potentially dangerous     function, Squid and the default certificate validation helper are vulnerable to a Denial of Service when     opening a TLS connection to an attacker-controlled server for HTTPS. This occurs because unrecognized     error values are mapped to NULL, but later code expects that each error value is mapped to a valid error     string.

    CVE-2020-15049:
    An issue was discovered in http/ContentLengthInterpreter.cc in Squid before 4.12 and 5.x before 5.0.3. A     Request Smuggling and Poisoning attack can succeed against the HTTP cache. The client sends an HTTP     request with a Content-Length header containing +\ - or an uncommon shell whitespace character prefix     to the length field-value.

    CVE-2020-15810:
    An issue was discovered in Squid before 4.13 and 5.x before 5.0.4. Due to incorrect data validation, HTTP     Request Smuggling attacks may succeed against HTTP and HTTPS traffic. This leads to cache poisoning. This     allows any client, including browser scripts, to bypass local security and poison the proxy cache and any     downstream caches with content from an arbitrary source. When configured for relaxed header parsing (the     default), Squid relays headers containing whitespace characters to upstream servers. When this occurs as a     prefix to a Content-Length header, the frame length specified will be ignored by Squid (allowing for a     conflicting length to be used from another Content-Length header) but relayed upstream.

    CVE-2020-15811:
    An issue was discovered in Squid before 4.13 and 5.x before 5.0.4. Due to incorrect data validation, HTTP     Request Splitting attacks may succeed against HTTP and HTTPS traffic. This leads to cache poisoning. This     allows any client, including browser scripts, to bypass local security and poison the browser cache and     any downstream caches with content from an arbitrary source. Squid uses a string search instead of parsing     the Transfer-Encoding header to find chunked encoding. This allows an attacker to hide a second request     inside Transfer-Encoding: it is interpreted by Squid as chunked and split out into a second request     delivered upstream. Squid will then deliver two distinct responses to the client, corrupting any     downstream caches.

    CVE-2020-24606:
    Squid before 4.13 and 5.x before 5.0.4 allows a trusted peer to perform Denial of Service by consuming all     available CPU cycles during handling of a crafted Cache Digest response message. This only occurs when     cache_peer is used with the cache digests feature. The problem exists because peerDigestHandleReply()     livelocking in peer_digest.cc mishandles EOF.

    CVE-2020-8449:
    An issue was discovered in Squid before 4.10. Due to incorrect input validation, it can interpret crafted     HTTP requests in unexpected ways to access server resources prohibited by earlier security filters.

    CVE-2020-8450:
    An issue was discovered in Squid before 4.10. Due to incorrect buffer management, a remote client can     cause a buffer overflow in a Squid instance acting as a reverse proxy.

Tenable has extracted the preceding description block directly from the Alibaba Cloud Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	名前	製品	ファミリー	公開日	更新日	深刻度
238736	TencentOS Server 3: squid:4 (TSSA-2022:0124)	Nessus	Tencent Local Security Checks	2025/6/16	2025/12/5	critical
356925	Rocky Linux 8.6 [CIQ] Security Update: squid / squid-debuginfo / squid-debugsource Multiple Vulnerabilities (ciqsa-2026_0262)	Nessus	Rocky Linux Local Security Checks	2026/10/1	2026/10/11	critical
176763	Amazon Linux AMI : squid (ALAS-2023-1754)	Nessus	Amazon Linux Local Security Checks	2023/6/6	2024/12/11	high
184691	Rocky Linux 8 : squid:4 (RLSA-2020:4743)	Nessus	Rocky Linux Local Security Checks	2023/11/6	2023/11/6	critical
223329	Linux Distros Unpatched Vulnerability : CVE-2020-14058	Nessus	Misc.	2025/3/4	2026/7/24	high
139912	Squid 2.x < 4.12 / 5.x < 5.0.3 (SQUID-2020:5, SQUID-2020:6 & SQUID-2020:7)	Nessus	Firewalls	2020/8/27	2021/1/4	high
153296	EulerOS 2.0 SP2 : squid (EulerOS-SA-2021-2433)	Nessus	Huawei Local Security Checks	2021/9/14	2023/11/30	high
145748	EulerOS 2.0 SP8 : squid (EulerOS-SA-2021-1172)	Nessus	Huawei Local Security Checks	2021/2/1	2024/1/25	high
142412	RHEL 8 : squid:4 (RHSA-2020:4743)	Nessus	Red Hat Local Security Checks	2020/11/4	2024/11/7	critical
236441	Alibaba Cloud Linux 3 : 0124: squid:4 (ALINUX3-SA-2022:0124)	Nessus	Alibaba Cloud Linux Local Security Checks	2025/5/14	2025/5/14	critical

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