The ACPI subsystem in the Linux kernel before 2.6.36.2 uses 0222 permissions for the debugfs custom_method file, which allows local users to gain privileges by placing a custom ACPI method in the ACPI interpreter tables, related to the acpi_debugfs_init function in drivers/acpi/debugfs.c.
http://lists.opensuse.org/opensuse-security-announce/2011-01/msg00000.html
http://lists.opensuse.org/opensuse-security-announce/2011-02/msg00000.html
http://openwall.com/lists/oss-security/2010/12/15/3
http://openwall.com/lists/oss-security/2010/12/15/7
https://bugzilla.redhat.com/show_bug.cgi?id=663542
http://secunia.com/advisories/42778
https://exchange.xforce.ibmcloud.com/vulnerabilities/64155
http://www.exploit-db.com/exploits/15774/