Updated firefox packages that fix multiple security issues are now available for Red Hat Enterprise Linux 4, 5, and 6. The Red Hat Security Response Team has rated this update as having critical security impact. Common Vulnerability Scoring System base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section. Description Mozilla Firefox is an open source web browser. XULRunner provides the XUL Runtime environment for Mozilla Firefox. A flaw was found in the way Firefox handled certain add-ons. A web page containing malicious content could cause an add-on to grant itself full browser privileges, which could lead to arbitrary code execution with the privileges of the user running Firefox. A cross-site scripting flaw was found in the way Firefox handled certain multibyte character sets. A web page containing malicious content could cause Firefox to run JavaScript code with the permissions of a different website. A flaw was found in the way Firefox handled large JavaScript scripts. A web page containing malicious JavaScript could cause Firefox to crash or, potentially, execute arbitrary code with the privileges of the user running Firefox. For technical details regarding these flaws, refer to the Mozilla security advisories for Firefox 3.6.24. You can find a link to the Mozilla advisories in the References section of this erratum. All Firefox users should upgrade to these updated packages, which contain Firefox version 3.6.24, which corrects these issues. After installing the update, Firefox must be restarted for the changes to take effect.