tmux 1.3 and 1.4 does not properly drop group privileges, which allows local users to gain utmp group privileges via a filename to the -S command-line option.
https://exchange.xforce.ibmcloud.com/vulnerabilities/66693
http://www.vupen.com/english/advisories/2011/1015
http://www.vupen.com/english/advisories/2011/1002
http://www.vupen.com/english/advisories/2011/0897
http://www.securityfocus.com/bid/47283
http://www.debian.org/security/2011/dsa-2212
http://secunia.com/advisories/44239
http://secunia.com/advisories/44081
http://lists.fedoraproject.org/pipermail/package-announce/2011-April/058548.html
http://lists.fedoraproject.org/pipermail/package-announce/2011-April/058452.html
http://lists.fedoraproject.org/pipermail/package-announce/2011-April/058367.html