Mozilla Firefox before 35.0, Firefox ESR 31.x before 31.4, Thunderbird before 31.4, and SeaMonkey before 2.32 do not properly interpret Set-Cookie headers within responses that have a 407 (aka Proxy Authentication Required) status code, which allows remote HTTP proxy servers to conduct session fixation attacks by providing a cookie name that corresponds to the session cookie of the origin server.
https://security.gentoo.org/glsa/201504-01
https://exchange.xforce.ibmcloud.com/vulnerabilities/99959
https://bugzilla.mozilla.org/show_bug.cgi?id=1095859
http://www.ubuntu.com/usn/USN-2460-1
http://www.securitytracker.com/id/1031534
http://www.securitytracker.com/id/1031533
http://www.securityfocus.com/bid/72046
http://www.oracle.com/technetwork/topics/security/bulletinapr2015-2511959.html
http://www.mozilla.org/security/announce/2014/mfsa2015-04.html
http://www.debian.org/security/2015/dsa-3132
http://www.debian.org/security/2015/dsa-3127
http://secunia.com/advisories/62790
http://secunia.com/advisories/62657
http://secunia.com/advisories/62446
http://secunia.com/advisories/62418
http://secunia.com/advisories/62316
http://secunia.com/advisories/62315
http://secunia.com/advisories/62313
http://secunia.com/advisories/62304
http://secunia.com/advisories/62293
http://secunia.com/advisories/62283
http://secunia.com/advisories/62274
http://secunia.com/advisories/62273
http://secunia.com/advisories/62259
http://secunia.com/advisories/62253
http://secunia.com/advisories/62250
http://secunia.com/advisories/62242
http://secunia.com/advisories/62237
http://rhn.redhat.com/errata/RHSA-2015-0047.html
http://rhn.redhat.com/errata/RHSA-2015-0046.html
http://lists.opensuse.org/opensuse-updates/2015-01/msg00071.html
http://lists.opensuse.org/opensuse-security-announce/2015-07/msg00031.html
http://lists.opensuse.org/opensuse-security-announce/2015-02/msg00002.html
http://lists.opensuse.org/opensuse-security-announce/2015-01/msg00036.html
http://lists.opensuse.org/opensuse-security-announce/2015-01/msg00033.html
http://lists.opensuse.org/opensuse-security-announce/2015-01/msg00032.html
http://lists.opensuse.org/opensuse-security-announce/2015-01/msg00014.html