Varnish before 3.0.5 allows remote attackers to cause a denial of service (child-process crash and temporary caching outage) via a GET request with trailing whitespace characters and no URI.
http://www.openwall.com/lists/oss-security/2013/10/30/5
http://www.debian.org/security/2012/dsa-2814
http://secunia.com/advisories/55746
http://secunia.com/advisories/55452
http://lists.opensuse.org/opensuse-updates/2013-11/msg00033.html
http://lists.opensuse.org/opensuse-updates/2013-11/msg00029.html
http://archives.neohapsis.com/archives/bugtraq/2013-10/0158.html