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 handled certain DOM JavaScript objects. An attacker could use this flaw to make JavaScript client or add-on code make incorrect, security sensitive decisions. Red Hat would like to thank the Mozilla project for reporting these issues. Upstream acknowledges Andre Bargull, Scoobidiver, Bobby Holley, Reuben Morais, Abhishek Arya, Ms2ger, Sachin Shinde, Aki Helin, Nils, and Boris Zbarsky as the original reporters of these issues. 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. All Thunderbird users should upgrade to this updated package, which contains Thunderbird version 17.0.9 ESR, which corrects these issues. After installing the update, Thunderbird must be restarted for the changes to take effect.