The Edge Side Includes (ESI) parser in Squid 3.x before 3.5.15 and 4.x before 4.0.7 does not check buffer limits during XML parsing, which allows remote HTTP servers to cause a denial of service (assertion failure and daemon exit) via a crafted XML document, related to esi/CustomParser.cc and esi/CustomParser.h.
https://usn.ubuntu.com/3557-1/
https://security.gentoo.org/glsa/201607-01
http://www.squid-cache.org/Versions/v4/changesets/squid-4-14549.patch
http://www.squid-cache.org/Versions/v3/3.5/changesets/squid-3.5-13993.patch
http://www.squid-cache.org/Advisories/SQUID-2016_2.txt
http://www.securitytracker.com/id/1035101
http://www.openwall.com/lists/oss-security/2016/02/26/2
http://rhn.redhat.com/errata/RHSA-2016-2600.html
http://lists.opensuse.org/opensuse-updates/2016-08/msg00069.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00040.html
http://lists.opensuse.org/opensuse-security-announce/2016-08/msg00010.html