A vulnerability was discovered in tigernvc, a Virtual Network Computing client and server implementation. The viewer implementation mishandles TLS certificate exceptions, storing the certificates as authorities, meaning that the owner of a certificate could impersonate any server after a client had added an exception.

For Debian 9 stretch, this problem has been fixed in version 1.7.0+dfsg-7+deb9u2.

We recommend that you upgrade your tigervnc packages.

For the detailed security status of tigervnc please refer to its security tracker page at:
https://security-tracker.debian.org/tracker/tigervnc

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA 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 tigervnc packages installed, the EulerOS installation on the remote host is affected by the following vulnerability :

  - In rfb/CSecurityTLS.cxx and rfb/CSecurityTLS.java in     TigerVNC before 1.11.0, viewers mishandle TLS     certificate exceptions. They store the certificates as     authorities, meaning that the owner of a certificate     could impersonate any server after a client had added     an exception.(CVE-2020-26117)

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 Ubuntu 20.04 ESM host has packages installed that are affected by a vulnerability as referenced in the USN-5965-1 advisory.

    It was discovered that TigerVNC mishandled TLS certificate exceptions. An attacker could use this     vulnerability to impersonate any server after a client had added an exception and obtain sensitive     information.

Tenable has extracted the preceding description block directly from the Ubuntu 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 CentOS Linux 8 host has packages installed that are affected by a vulnerability as referenced in the CESA-2021:1783 advisory.

  - tigervnc: certificate exceptions stored as authorities (CVE-2020-26117)

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 tigervnc packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - TigerVNC version prior to 1.10.1 is vulnerable to stack     use-after-return, which occurs due to incorrect usage     of stack memory in ZRLEDecoder. If decoding routine     would throw an exception, ZRLEDecoder may try to access     stack variable, which has been already freed during the     process of stack unwinding. Exploitation of this     vulnerability could potentially result into remote code     execution. This attack appear to be exploitable via     network connectivity.(CVE-2019-15691)

  - TigerVNC version prior to 1.10.1 is vulnerable to heap     buffer overflow. Vulnerability could be triggered from     CopyRectDecoder due to incorrect value checks.
    Exploitation of this vulnerability could potentially     result into remote code execution. This attack appear     to be exploitable via network     connectivity.(CVE-2019-15692)

  - TigerVNC version prior to 1.10.1 is vulnerable to heap     buffer overflow, which occurs in     TightDecoder::FilterGradient. Exploitation of this     vulnerability could potentially result into remote code     execution. This attack appear to be exploitable via     network connectivity.(CVE-2019-15693)

  - TigerVNC version prior to 1.10.1 is vulnerable to heap     buffer overflow, which could be triggered from     DecodeManager::decodeRect. Vulnerability occurs due to     the signdness error in processing MemOutStream.
    Exploitation of this vulnerability could potentially     result into remote code execution. This attack appear     to be exploitable via network     connectivity.(CVE-2019-15694)

  - TigerVNC version prior to 1.10.1 is vulnerable to stack     buffer overflow, which could be triggered from     CMsgReader::readSetCursor. This vulnerability occurs     due to insufficient sanitization of PixelFormat. Since     remote attacker can choose offset from start of the     buffer to start writing his values, exploitation of     this vulnerability could potentially result into remote     code execution. This attack appear to be exploitable     via network connectivity.(CVE-2019-15695)

  - In rfb/CSecurityTLS.cxx and rfb/CSecurityTLS.java in     TigerVNC before 1.11.0, viewers mishandle TLS     certificate exceptions. They store the certificates as     authorities, meaning that the owner of a certificate     could impersonate any server after a client had added     an exception.(CVE-2020-26117)

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

  - In rfb/CSecurityTLS.cxx and rfb/CSecurityTLS.java in     TigerVNC before 1.11.0, viewers mishandle TLS     certificate exceptions. They store the certificates as     authorities, meaning that the owner of a certificate     could impersonate any server after a client had added     an exception.(CVE-2020-26117)

  - TigerVNC version prior to 1.10.1 is vulnerable to stack     use-after-return, which occurs due to incorrect usage     of stack memory in ZRLEDecoder. If decoding routine     would throw an exception, ZRLEDecoder may try to access     stack variable, which has been already freed during the     process of stack unwinding. Exploitation of this     vulnerability could potentially result into remote code     execution. This attack appear to be exploitable via     network connectivity.(CVE-2019-15691)

  - TigerVNC version prior to 1.10.1 is vulnerable to heap     buffer overflow. Vulnerability could be triggered from     CopyRectDecoder due to incorrect value checks.
    Exploitation of this vulnerability could potentially     result into remote code execution. This attack appear     to be exploitable via network     connectivity.(CVE-2019-15692)

  - TigerVNC version prior to 1.10.1 is vulnerable to heap     buffer overflow, which occurs in     TightDecoder::FilterGradient. Exploitation of this     vulnerability could potentially result into remote code     execution. This attack appear to be exploitable via     network connectivity.(CVE-2019-15693)

  - TigerVNC version prior to 1.10.1 is vulnerable to heap     buffer overflow, which could be triggered from     DecodeManager::decodeRect. Vulnerability occurs due to     the signdness error in processing MemOutStream.
    Exploitation of this vulnerability could potentially     result into remote code execution. This attack appear     to be exploitable via network     connectivity.(CVE-2019-15694)

  - TigerVNC version prior to 1.10.1 is vulnerable to stack     buffer overflow, which could be triggered from     CMsgReader::readSetCursor. This vulnerability occurs     due to insufficient sanitization of PixelFormat. Since     remote attacker can choose offset from start of the     buffer to start writing his values, exploitation of     this vulnerability could potentially result into remote     code execution. This attack appear to be exploitable     via network connectivity.(CVE-2019-15695)

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 tigervnc package installed, the EulerOS installation on the remote host is affected by the following vulnerability :

  - In rfb/CSecurityTLS.cxx and rfb/CSecurityTLS.java in     TigerVNC before 1.11.0, viewers mishandle TLS     certificate exceptions. They store the certificates as     authorities, meaning that the owner of a certificate     could impersonate any server after a client had added     an exception.(CVE-2020-26117)

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.

This update for tigervnc fixes the following issues :

CVE-2020-26117: Server certificates were stored as certiticate authorities, allowing malicious owners of these certificates to impersonate any server after a client had added an exception (bsc#1176733)

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

The remote Oracle Linux 8 host has packages installed that are affected by a vulnerability as referenced in the ELSA-2021-1783 advisory.

    [1.11.0-6]
    - Use GNOME as default session       Resolves: bz#1853608

    [1.11.0-5]
    - Make sure we log properly output to journal (actually log to syslog)       Resolves: bz#1841537

    [1.11.0-4]
    - Make sure we log properly output to journal       Resolves: bz#1841537

    [1.11.0-3]
    - vncserver: ignore new 'session' parameter from the new systemd support       Resolves: bz#1897504

    [1.11.0-2]
    - Revert removal of vncserver       Resolves: bz#1897504
    - Correctly start vncsession as a daemon       Resolves: bz#1897498

    [1.11.0-1]
    - Update to 1.11.0       Resolves: bz#1880985
    - Backport fix to allow Tigervnc use boolean values in config files       Resolves: bz#1883415

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

Note that Nessus has not tested for this issue 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
141246	Debian DLA-2396-1 : tigervnc security update	Nessus	Debian Local Security Checks	2020/10/7	2020/10/19	high
144149	EulerOS 2.0 SP8 : tigervnc (EulerOS-SA-2020-2536)	Nessus	Huawei Local Security Checks	2020/12/14	2024/2/2	high
173051	Ubuntu 20.04 ESM : TigerVNC vulnerability (USN-5965-1)	Nessus	Ubuntu Local Security Checks	2023/3/21	2024/8/28	high
149753	CentOS 8 : tigervnc (CESA-2021:1783)	Nessus	CentOS Local Security Checks	2021/5/19	2021/6/2	high
145143	EulerOS 2.0 SP3 : tigervnc (EulerOS-SA-2021-1127)	Nessus	Huawei Local Security Checks	2021/1/20	2024/1/29	high
146169	EulerOS 2.0 SP5 : tigervnc (EulerOS-SA-2021-1237)	Nessus	Huawei Local Security Checks	2021/2/4	2024/1/23	high
142274	EulerOS 2.0 SP9 : tigervnc (EulerOS-SA-2020-2422)	Nessus	Huawei Local Security Checks	2020/11/3	2024/2/12	high
143643	SUSE SLED15 / SLES15 Security Update : tigervnc (SUSE-SU-2020:2880-1)	Nessus	SuSE Local Security Checks	2020/12/9	2024/2/6	high
149917	Oracle Linux 8 : tigervnc (ELSA-2021-1783)	Nessus	Oracle Linux Local Security Checks	2021/5/26	2024/10/23	high

検出

プラグインの検索

high

high

high

high

high

high

high

high

high