The CSSLoaderImpl::DoSheetComplete function in layout/style/nsCSSLoader.cpp in Mozilla Firefox 3.0.x before 3.0.18, 3.5.x before 3.5.8, and 3.6.x before 3.6.2; Thunderbird before 3.0.2; and SeaMonkey before 2.0.3 changes the case of certain strings in a stylesheet before adding this stylesheet to the XUL cache, which might allow remote attackers to modify the browser's font and other CSS attributes, and potentially disrupt rendering of a web page, by forcing the browser to perform this erroneous stylesheet caching.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A8431
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11391
https://bugzilla.mozilla.org/show_bug.cgi?id=535806
http://www.vupen.com/english/advisories/2010/0692
http://www.securityfocus.com/bid/38918
http://www.mozilla.org/security/announce/2010/mfsa2010-14.html