Severity: Critical
CVSS Score: 9.3
Mozilla Firefox before 3.6.26 and 4.x through 9.0, Thunderbird before 3.1.18 and 5.0 through 9.0, and SeaMonkey before 2.7 allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via a malformed XSLT stylesheet that is embedded in a document.