The mem_write function in the Linux kernel before 3.2.2, when ASLR is disabled, does not properly check permissions when writing to /proc/<pid>/mem, which allows local users to gain privileges by modifying process memory, as demonstrated by Mempodipper.
http://secunia.com/advisories/47708
http://ubuntu.com/usn/usn-1336-1
http://www.kb.cert.org/vuls/id/470151
http://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.2.2
http://www.openwall.com/lists/oss-security/2012/01/18/1
http://www.openwall.com/lists/oss-security/2012/01/18/2
http://www.openwall.com/lists/oss-security/2012/01/19/4
http://www.openwall.com/lists/oss-security/2012/01/22/4
http://www.redhat.com/support/errata/RHSA-2012-0052.html
http://www.redhat.com/support/errata/RHSA-2012-0061.html