{"id":"CVE-2026-84121","state":"PUBLISHED","title":"Sandbox escape due to use-after-free in the DOM: Security component","description":"Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.","publishedAt":"2026-09-01T12:18:41.535Z","updatedAt":"2026-09-02T03:55:38.279Z","severity":{"score":9.6,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H","source":"CISA-ADP"},"assigner":"mozilla","products":["Mozilla Firefox","Mozilla Thunderbird"],"affected":[{"vendor":"Mozilla","product":"Firefox","versions":[{"version":"115.40","status":"unaffected","lessThanOrEqual":"115.*","versionType":"rpm"},{"version":"140.15","status":"unaffected","lessThanOrEqual":"140.*","versionType":"rpm"},{"version":"153.2","status":"unaffected","lessThanOrEqual":"153.*","versionType":"rpm"},{"version":"155","status":"unaffected","lessThanOrEqual":"*","versionType":"rpm"}]},{"vendor":"Mozilla","product":"Thunderbird","versions":[{"version":"140.15","status":"unaffected","lessThanOrEqual":"140.*","versionType":"rpm"},{"version":"153.2","status":"unaffected","lessThanOrEqual":"153.*","versionType":"rpm"},{"version":"155","status":"unaffected","lessThanOrEqual":"*","versionType":"rpm"}]}],"references":["https://bugzilla.mozilla.org/show_bug.cgi?id=2059018","https://www.mozilla.org/security/advisories/mfsa2026-82/","https://www.mozilla.org/security/advisories/mfsa2026-83/","https://www.mozilla.org/security/advisories/mfsa2026-84/","https://www.mozilla.org/security/advisories/mfsa2026-85/","https://www.mozilla.org/security/advisories/mfsa2026-86/","https://www.mozilla.org/security/advisories/mfsa2026-87/","https://www.mozilla.org/security/advisories/mfsa2026-88/"],"weaknesses":["CWE-416"],"ingestedAt":"2026-10-29T20:13:15.269Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/84xxx/CVE-2026-84121.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-84121","state":"PUBLISHED","datePublished":"2026-09-01T12:18:41.535Z","dateUpdated":"2026-09-02T03:55:38.279Z","assignerShortName":"mozilla","assignerOrgId":"f16b083a-5664-49f3-a51e-8d479e5ed7fe","dateReserved":"2026-09-01T07:25:11.012Z"},"containers":{"cna":{"title":"Sandbox escape due to use-after-free in the DOM: Security component","descriptions":[{"lang":"en","value":"Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2."}],"affected":[{"vendor":"Mozilla","product":"Firefox","versions":[{"version":"115.40","status":"unaffected","lessThanOrEqual":"115.*","versionType":"rpm"},{"version":"140.15","status":"unaffected","lessThanOrEqual":"140.*","versionType":"rpm"},{"version":"153.2","status":"unaffected","lessThanOrEqual":"153.*","versionType":"rpm"},{"version":"155","status":"unaffected","lessThanOrEqual":"*","versionType":"rpm"}]},{"vendor":"Mozilla","product":"Thunderbird","versions":[{"version":"140.15","status":"unaffected","lessThanOrEqual":"140.*","versionType":"rpm"},{"version":"153.2","status":"unaffected","lessThanOrEqual":"153.*","versionType":"rpm"},{"version":"155","status":"unaffected","lessThanOrEqual":"*","versionType":"rpm"}]}],"references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=2059018"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-82/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-83/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-84/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-85/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-86/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-87/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2026-88/"}],"providerMetadata":{"shortName":"mozilla","orgId":"f16b083a-5664-49f3-a51e-8d479e5ed7fe","dateUpdated":"2026-09-01T21:44:08.642Z"},"credits":[{"lang":"en","value":"Yaqoub Aldurayhim"}]},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"CHANGED","version":"3.1","baseScore":9.6,"attackVector":"NETWORK","baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H","integrityImpact":"HIGH","userInteraction":"REQUIRED","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"HIGH"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-09-01T00:00:00+00:00","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3","id":"CVE-2026-84121"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","type":"CWE","lang":"en","description":"CWE-416 Use After Free"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-02T03:55:38.279Z"}}]}}}