Mozilla Firefox is an open source web browser. XULRunner provides the XULRuntime environment for Mozilla Firefox.A flaw was found in the processing of malformed web content. A web pagecontaining malicious content could cause Firefox to crash or, potentially,execute arbitrary code with the privileges of the user running Firefox.(CVE-2015-4497)A flaw was found in the way Firefox handled installation of add-ons.An attacker could use this flaw to bypass the add-on installation prompt,and trick the user inso installing an add-on from a malicious source.(CVE-2015-4498)Red Hat would like to thank the Mozilla project for reporting these issues.Upstream acknowledges Jean-Max Reymond, Ucha Gobejishvili, and Bas Venis asthe original reporters of these issues.All Firefox users should upgrade to these updated packages, which containFirefox version 38.2.1 ESR, which corrects these issues. After installingthe update, Firefox must be restarted for the changes to take effect.