{"id":"CVE-2026-100816","title":"Site isolation issue in the DOM: Networking component","summary":"Site isolation issue in the DOM: Networking component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.","severity":"high","cvss":8.1,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","cwe":["CWE-346"],"vendor":"mozilla","product":"firefox","affected":["firefox < 153.4.0","firefox >= 154.0.0, < 157.0.0","thunderbird < 153.4.0","thunderbird >= 154.0, < 157.0"],"patched":["firefox 157.0.0","thunderbird 157.0"],"published":"2026-09-29","updated":"2026-10-05","sourceUpdated":"2026-10-05T16:59:58.540","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-100816","references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=2068648","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-100/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-101/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-103/","label":"security@mozilla.org"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-97/","label":"security@mozilla.org"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100816.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-100816"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2543147"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100816"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100816"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-97/#CVE-2026-100816"}],"tags":["nvd","cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00153,"epssPercentile":0.04383,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-01T15:38:39.482643Z"},"ingestedAt":"2026-09-29T13:34:31.675Z","scores":{"nvd":8.1,"vendor":6.1},"slug":"CVE-2026-100816","body":"## Overview\n\nSite isolation issue in the DOM: Networking component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 153.4, and Firefox 157.\n\n## Affected\n\n- `firefox < 153.4.0`\n- `firefox >= 154.0.0, < 157.0.0`\n- `thunderbird < 153.4.0`\n- `thunderbird >= 154.0, < 157.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `firefox 157.0.0`\n- `thunderbird 157.0`\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100816.json)","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":44.6,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":214563,"id":"CVE-2026-100816","ts":1790881065792,"field":"cvss","old":null,"new":"8.1"},{"seq":214562,"id":"CVE-2026-100816","ts":1790881065792,"field":"severity","old":"none","new":"high"}]}