An updated thunderbird package that fixes several security issues is now available for Red Hat Enterprise Linux 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 Thunderbird is a standalone mail and newsgroup client. Several flaws were found in the processing of malformed HTML content. Malicious HTML content could cause Thunderbird to crash or, potentially, execute arbitrary code with the privileges of the user running Thunderbird. A dangling pointer flaw was found in the Thunderbird Scalable Vector Graphics text manipulation routine. An HTML mail message containing a malicious SVG image could cause Thunderbird to crash or, potentially, execute arbitrary code with the privileges of the user running Thunderbird. A dangling pointer flaw was found in the way Thunderbird handled a certain Document Object Model element. An HTML mail message containing malicious content could cause Thunderbird to crash or, potentially, execute arbitrary code with the privileges of the user running Thunderbird. All Thunderbird users should upgrade to this updated package, which resolves these issues. All running instances of Thunderbird must be restarted for the update to take effect.