The idnsGrokReply function in Squid before 3.1.16 does not properly free memory, which allows remote attackers to cause a denial of service (daemon abort) via a DNS reply containing a CNAME record that references another CNAME record that contains an empty A record.
bugs.squid-cache.org/show_bug.cgi?id=3237#c12
lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html
lists.opensuse.org/opensuse-security-announce/2016-08/msg00040.html
secunia.com/advisories/46609
secunia.com/advisories/47459
www.mandriva.com/security/advisories?name=MDVSA-2011:193
www.openwall.com/lists/oss-security/2011/10/31/5
www.openwall.com/lists/oss-security/2011/11/01/3
www.redhat.com/support/errata/RHSA-2011-1791.html
www.securitytracker.com/id?1026265
www.squid-cache.org/Versions/v3/3.1/changesets/SQUID_3_1_16.html