The cycle collection (CC) implementation in Mozilla Firefox before 25.0, Firefox ESR 24.x before 24.1, Thunderbird before 24.1, and SeaMonkey before 2.22 does not properly determine the thread for release of an image object, which allows remote attackers to execute arbitrary code or cause a denial of service (race condition and application crash) via a large HTML document containing IMG elements, as demonstrated by the Never-Ending Reddit on reddit.com.
lists.opensuse.org/opensuse-security-announce/2013-11/msg00005.html
lists.opensuse.org/opensuse-security-announce/2013-11/msg00006.html
www.mozilla.org/security/announce/2013/mfsa2013-97.html
bugzilla.mozilla.org/show_bug.cgi?id=910881
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A19066
security.gentoo.org/glsa/201504-01