An updated thunderbird package that fixes three security issues is now available for Red Hat Enterprise Linux 5 and 6. Red Hat Product Security 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. Two flaws were found in the processing of malformed web content. A web page containing malicious content could cause Firefox to crash or, potentially, execute arbitrary code with the privileges of the user running Firefox. It was found that the Beacon interface implementation in Thunderbird did not follow the Cross-Origin Resource Sharing specification. A web page containing malicious content could allow a remote attacker to conduct a Cross-Site Request Forgery attack. 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 Christian Holler, Patrick McManus, Muneaki Nishimura, and Xiaofeng Zheng as the original reporters of these issues. For technical details regarding these flaws, refer to the Mozilla security advisories for Thunderbird 31.4.0. 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 31.4.0, which corrects these issues. After installing the update, Thunderbird must be restarted for the changes to take effect.