Mozilla Thunderbird is a standalone mail and newsgroup client. Several flaws were found in the processing of malformed web content. A web page containing malicious content could cause Thunderbird to crash or, potentially, execute arbitrary code with the privileges of the user running Thunderbird. Multiple security flaws were found in the graphite2 font library shipped with Thunderbird. A web page containing malicious content could cause Thunderbird to crash or, potentially, execute arbitrary code with the privileges of the user running Thunderbird. Red Hat would like to thank the Mozilla project for reporting these issues. Upstream acknowledges Bob Clary, Christoph Diehl, Christian Holler, Andrew McCreight, Daniel Holbert, Jesse Ruderman, Randell Jesup, Nicolas Golubovic, Jose Martinez, Romina Santillan, ca0nguyen, lokihardt, Nicolas Gregoire, the Communications Electronics Security Group of the GCHQ, Holger Fuhrmannek, Ronald Crane, and Tyson Smith as the original reporters of these issues. For technical details regarding these flaws, refer to the Mozilla security advisories for Thunderbird 38.7.0. 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 38.7.0, which corrects these issues. After installing the update, Thunderbird must be restarted for the changes to take effect.