{"id":"CVE-2026-109759","title":"Site isolation issue in the Networking component","summary":"Site isolation issue in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.","severity":"high","published":"2026-10-13","updated":"2026-10-13","sourceUpdated":"2026-10-13T19:18:40.063","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-109759","references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=2070252","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-106/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-108/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-109/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-110/","label":"security@mozilla.org"}],"tags":["nvd","cve.org"],"ingestedAt":"2026-10-13T13:27:04.010Z","vendor":"Mozilla","product":"Firefox","affected":["Firefox","Thunderbird"],"epss":0.00178,"epssPercentile":0.07314,"cvss":8.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-19T12:28:42.473569Z"},"cvssSource":"adp","slug":"CVE-2026-109759","body":"## Overview\n\nSite isolation issue in the Networking component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":44.6,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":224936,"id":"CVE-2026-109759","ts":1792416581165,"field":"cvss","old":null,"new":"8.1"},{"seq":224935,"id":"CVE-2026-109759","ts":1792416581165,"field":"severity","old":"none","new":"high"}]}