Mozilla Firefox is an open source web browser. XULRunner provides the XULRuntime environment for Mozilla Firefox.Multiple security flaws were found in the graphite2 font library shippedwith Firefox. A web page containing malicious content could cause Firefoxto crash or, potentially, execute arbitrary code with the privileges of theuser running Firefox. (CVE-2016-1521, CVE-2016-1522, CVE-2016-1523)All Firefox users should upgrade to these updated packages, which containFirefox version 38.6.1 ESR, which corrects these issues. After installingthe update, Firefox must be restarted for the changes to take effect.