Multiple unspecified vulnerabilities in the browser engine in Mozilla Firefox before 39.0, Firefox ESR 38.x before 38.1, and Thunderbird before 38.1 allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via unknown vectors.

Mozilla Firefox 38.0 and Firefox ESR 38.0 allow user-assisted remote attackers to read arbitrary files or execute arbitrary JavaScript code with chrome privileges via a crafted web site that is accessed with unspecified mouse and keyboard actions. NOTE: this vulnerability exists because of a CVE-2015-0821 regression.