lib/rfc1035.c in Squid 2.x, 3.0 through 3.0.STABLE22, and 3.1 through 3.1.0.15 allows remote attackers to cause a denial of service (assertion failure) via a crafted DNS packet that only contains a header.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11270
https://exchange.xforce.ibmcloud.com/vulnerabilities/56001
http://www.vupen.com/english/advisories/2010/0260
http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.1-9853.patch
http://www.squid-cache.org/Versions/v3/3.0/changesets/squid-3.0-9163.patch
http://www.squid-cache.org/Versions/v2/HEAD/changesets/12597.patch
http://www.squid-cache.org/Advisories/SQUID-2010_1.txt
http://www.securitytracker.com/id?1023520
http://www.securityfocus.com/bid/37522
http://secunia.com/advisories/38455
http://secunia.com/advisories/38451
http://events.ccc.de/congress/2009/Fahrplan/attachments/1483_26c3_ipv4_fuckups.pdf