An updated thunderbird package that fixes several security issues is now available for Red Hat Enterprise Linux 5 and 6. The Red Hat Security Response Team has rated this update as having important 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. Mozilla Thunderbird is a standalone mail and newsgroup client. Several flaws were found in the processing of malformed content. Malicious content could cause Thunderbird to crash or, potentially, execute arbitrary code with the privileges of the user running Thunderbird. A flaw was found in the way Thunderbird rendered web content with missing character encoding information. An attacker could use this flaw to possibly bypass same-origin inheritance and perform cross site-scripting attacks. It was found that certain malicious web content could bypass restrictions applied by sandboxed iframes. An attacker could combine this flaw with other vulnerabilities to execute arbitrary code with the privileges of the user running Thunderbird. Note: All of the above issues cannot be exploited by a specially crafted HTML mail message as JavaScript is disabled by default for mail messages. They could be exploited another way in Thunderbird, for example, when viewing the full remote content of an RSS feed. Red Hat would like to thank the Mozilla project for reporting these issues. Upstream acknowledges Ben Turner, Bobby Holley, Jesse Ruderman, Christian Holler, Masato Kinugawa, Daniel Veditz, Jesse Schwartzentruber, Nils, Tyson Smith, and Atte Kettunen as the original reporters of these issues. For technical details regarding these flaws, refer to the Mozilla security advisories for Thunderbird 24.2.0 ESR. You can find a link to the Mozilla advisories in the References section of this erratum. All Thunderbird users should upgrade to this updated package, which contains Thunderbird version 24.2.0 ESR, which corrects these issues. After installing the update, Thunderbird must be restarted for the changes to take effect.