firefox is vulnerable to arbitrary code execution. A flaw was found in the way Firefox handles malformed JavaScript. A website with an object containing malicious JavaScript could execute that JavaScript with the privileges of the user running Firefox.
secunia.com/advisories/36670
secunia.com/advisories/36671
secunia.com/advisories/36757
secunia.com/advisories/37098
www.debian.org/security/2009/dsa-1886
www.mozilla.org/security/announce/2009/mfsa2009-51.html
www.mozilla.org/security/known-vulnerabilities/firefox30.html#firefox3.0.14
www.novell.com/linux/security/advisories/2009_48_firefox.html
www.redhat.com/security/updates/classification/#critical
www.redhat.com/support/errata/RHSA-2009-1430.html
www.securityfocus.com/bid/36343
www.securitytracker.com/id?1022873
access.redhat.com/errata/RHSA-2009:1430
bugzilla.mozilla.org/show_bug.cgi?id=454363
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10390
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6250