firefox is vulnerable to arbitrary code execution. The vulnerability exists as it was found that a malicious web page could execute arbitrary code with the privileges of the user running Firefox if the user dropped a tab onto the malicious web page.
lists.opensuse.org/opensuse-security-announce/2011-08/msg00023.html
lists.opensuse.org/opensuse-security-announce/2011-08/msg00027.html
www.debian.org/security/2011/dsa-2295
www.debian.org/security/2011/dsa-2296
www.debian.org/security/2011/dsa-2297
www.mandriva.com/security/advisories?name=MDVSA-2011:127
www.mozilla.org/security/announce/2011/mfsa2011-30.html
www.mozilla.org/security/known-vulnerabilities/firefox36.html#firefox3.6.20
www.redhat.com/support/errata/RHSA-2011-1164.html
access.redhat.com/errata/RHSA-2011:1164
access.redhat.com/security/updates/classification/#critical
bugzilla.mozilla.org/show_bug.cgi?id=572129
oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A14358