{"id":"CVE-2026-109739","title":"Privilege escalation in the WebExtensions component","summary":"Privilege escalation in the WebExtensions component. This vulnerability was fixed in Firefox 158 and Thunderbird 158.","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-269"],"published":"2026-10-13","updated":"2026-10-14","sourceUpdated":"2026-10-14T16:17:37.327","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-109739","references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=2049069","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-106/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-109/","label":"security@mozilla.org"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-10-13T13:27:04.003Z","vendor":"Mozilla","product":"Firefox","affected":["Firefox","Thunderbird"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-14T03:59:06.635051Z"},"epss":0.00369,"epssPercentile":0.30594,"slug":"CVE-2026-109739","body":"## Overview\n\nPrivilege escalation in the WebExtensions component. This vulnerability was fixed in Firefox 158 and Thunderbird 158.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":220318,"id":"CVE-2026-109739","ts":1791996106581,"field":"cvss","old":null,"new":"8.8"},{"seq":220317,"id":"CVE-2026-109739","ts":1791996106581,"field":"severity","old":"none","new":"high"}]}