dns_internal.cc in Squid 3.1.6, when IPv6 DNS resolution is not enabled, accesses an invalid socket during an IPv4 TCP DNS query, which allows remote attackers to cause a denial of service (assertion failure and daemon exit) via vectors that trigger an IPv4 DNS response with the TC bit set.
https://bugzilla.redhat.com/show_bug.cgi?id=626927
http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.1-10072.patch
http://www.openwall.com/lists/oss-security/2010/08/25/6
http://www.openwall.com/lists/oss-security/2010/08/25/2
http://www.openwall.com/lists/oss-security/2010/08/24/7
http://www.openwall.com/lists/oss-security/2010/08/24/6
http://marc.info/?l=squid-users&m=128263555724981&w=2
http://bugs.squid-cache.org/show_bug.cgi?id=3021
http://bugs.squid-cache.org/show_bug.cgi?id=3009