The oggplay_data_handle_theora_frame function in media/liboggplay/src/liboggplay/oggplay_data.c in liboggplay, as used in Mozilla Firefox 3.5.x before 3.5.4, attempts to reuse an earlier frame data structure upon encountering a decoding error for the first frame, which allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) or possibly execute arbitrary code via a crafted .ogg video file.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6443
https://bugzilla.mozilla.org/show_bug.cgi?id=500311
http://www.vupen.com/english/advisories/2009/3334
http://www.mozilla.org/security/announce/2009/mfsa2009-63.html
http://www.mandriva.com/security/advisories?name=MDVSA-2009:294
http://sunsolve.sun.com/search/document.do?assetkey=1-26-272909-1