Mozilla Firefox before 23.0 and SeaMonkey before 2.20 allow remote attackers to cause a denial of service (application crash) via a crafted WAV file that is not properly handled by the nsCString::CharAt function.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A18803
https://bugzilla.mozilla.org/show_bug.cgi?id=879924
http://www.mozilla.org/security/announce/2013/mfsa2013-67.html