CVE 2015-2724
Multiple unspecified vulnerabilities in the browser engine in Mozilla Firefox before 39.0, Firefox ESR 31.x before 31.8 and 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.
See the 
CVE page on Mitre.org
for more details.
