firefox is vulnerable to arbitrary code execution. The vulnerability exists as a web page containing malicious content could cause Firefox to crash or, potentially, execute arbitrary code with the privileges of the user running Firefox.
www.mozilla.org/security/announce/2010/mfsa2010-39.html
www.mozilla.org/security/known-vulnerabilities/firefox36.html#firefox3.6.7
www.redhat.com/security/updates/classification/#critical
www.securityfocus.com/archive/1/512514
www.securityfocus.com/bid/41852
www.zerodayinitiative.com/advisories/ZDI-10-133/
access.redhat.com/errata/RHSA-2010:0547
bugzilla.mozilla.org/show_bug.cgi?id=574059
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11680