{"id":"CVE-2026-100820","title":"Privilege escalation in the Address Bar component","summary":"Privilege escalation in the Address Bar component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","cwe":["CWE-269","CWE-15"],"vendor":"mozilla","product":"firefox","affected":["firefox < 140.17.0","firefox >= 141.0, < 153.4.0","firefox >= 154.0.0, < 157.0.0","thunderbird < 140.17.0","thunderbird >= 141.0, < 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":"2026-10-05T14:06:39.917","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-100820","references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=2071645","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/mfsa2026-102/","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://www.mozilla.org/security/advisories/mfsa2026-99/","label":"security@mozilla.org"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100820.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-100820"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2543121"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100820"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100820"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-102/#CVE-2026-100820"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-99/#CVE-2026-100820"},{"url":"https://access.redhat.com/errata/RHSA-2026:85240"},{"url":"https://access.redhat.com/errata/RHSA-2026:76764"},{"url":"https://access.redhat.com/errata/RHSA-2026:80674"},{"url":"https://access.redhat.com/errata/RHSA-2026:76850"},{"url":"https://access.redhat.com/errata/RHSA-2026:85243"},{"url":"https://access.redhat.com/errata/RHSA-2026:85242"},{"url":"https://access.redhat.com/errata/RHSA-2026:85241"},{"url":"https://access.redhat.com/errata/RHSA-2026:85244"},{"url":"https://access.redhat.com/errata/RHSA-2026:76761"},{"url":"https://access.redhat.com/errata/RHSA-2026:80694"}],"tags":["nvd","cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00238,"epssPercentile":0.14836,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-09-29T13:49:57.920647Z"},"ingestedAt":"2026-09-29T13:34:31.676Z","scores":{"nvd":8.8,"vendor":6.1},"slug":"CVE-2026-100820","body":"## Overview\n\nPrivilege escalation in the Address Bar component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.\n\n## Affected\n\n- `firefox < 140.17.0`\n- `firefox >= 141.0, < 153.4.0`\n- `firefox >= 154.0.0, < 157.0.0`\n- `thunderbird < 140.17.0`\n- `thunderbird >= 141.0, < 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- **RHSA-2026:85240** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0) · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:85240)\n- **RHSA-2026:76764** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-10-06 · [advisory](https://access.redhat.com/errata/RHSA-2026:76764)\n- **RHSA-2026:80674** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10) · released 2026-10-12 · [advisory](https://access.redhat.com/errata/RHSA-2026:80674)\n- **RHSA-2026:76850** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8) · released 2026-10-06 · [advisory](https://access.redhat.com/errata/RHSA-2026:76850)\n- **RHSA-2026:85243** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream AUS (v.8.4), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:85243)\n- **RHSA-2026:85242** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.2) · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:85242)\n- **RHSA-2026:85241** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.4) · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:85241)\n- **RHSA-2026:85244** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v.9.6) · released 2026-10-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:85244)\n- **RHSA-2026:76761** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-10-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:76761)\n- **RHSA-2026:80694** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 9) · released 2026-10-12 · [advisory](https://access.redhat.com/errata/RHSA-2026:80694)\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8 · updated 2026-10-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100820.json)","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":212700,"id":"CVE-2026-100820","ts":1790692644253,"field":"cvss","old":null,"new":"8.8"},{"seq":212699,"id":"CVE-2026-100820","ts":1790692644253,"field":"severity","old":"none","new":"high"}]}