Mozilla Firefox 4.x through 13.0, Firefox ESR 10.x before 10.0.6, Thunderbird 5.0 through 13.0, Thunderbird ESR 10.x before 10.0.6, and SeaMonkey before 2.11 do not properly handle duplicate values in X-Frame-Options headers, which makes it easier for remote attackers to conduct clickjacking attacks via a FRAME element referencing a web site that produces these duplicate values.

Mozilla Firefox 4.x through 13.0 and Firefox ESR 10.x before 10.0.6 do not have the same context-menu restrictions for data: URLs as for javascript: URLs, which allows remote attackers to conduct cross-site scripting (XSS) attacks via a crafted URL.

Mozilla Firefox 4.x through 13.0 and Firefox ESR 10.x before 10.0.6 do not properly establish the security context of a feed: URL, which allows remote attackers to bypass unspecified cross-site scripting (XSS) protection mechanisms via a feed:javascript: URL.

Multiple unspecified vulnerabilities in the browser engine in Mozilla Firefox 4.x through 13.0, Firefox ESR 10.x before 10.0.6, Thunderbird 5.0 through 13.0, Thunderbird ESR 10.x before 10.0.6, and SeaMonkey before 2.11 allow remote attackers to cause a denial of service (memory corruption and application crash) or possibly execute arbitrary code via unknown vectors.