CVE-2026-84121

{"id": "CVE-2026-84121", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-84121", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-09-01T00:00:00+00:00"}}], "cvssMetricV31": [{"type": "Secondary", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "cvssData": {"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"}, "impactScore": 6.0, "exploitabilityScore": 2.8}]}, "affected": [{"source": "security@mozilla.org", "affectedData": [{"vendor": "Mozilla", "product": "Firefox", "versions": [{"status": "unaffected", "version": "115.40", "versionType": "rpm", "lessThanOrEqual": "115.*"}, {"status": "unaffected", "version": "140.15", "versionType": "rpm", "lessThanOrEqual": "140.*"}, {"status": "unaffected", "version": "153.2", "versionType": "rpm", "lessThanOrEqual": "153.*"}, {"status": "unaffected", "version": "155", "versionType": "rpm", "lessThanOrEqual": "*"}]}, {"vendor": "Mozilla", "product": "Thunderbird", "versions": [{"status": "unaffected", "version": "140.15", "versionType": "rpm", "lessThanOrEqual": "140.*"}, {"status": "unaffected", "version": "153.2", "versionType": "rpm", "lessThanOrEqual": "153.*"}, {"status": "unaffected", "version": "155", "versionType": "rpm", "lessThanOrEqual": "*"}]}]}], "published": "2026-09-01T13:20:05.933", "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2059018", "tags": ["Permissions Required"], "source": "security@mozilla.org"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-82/", "tags": ["Vendor Advisory"], "source": "security@mozilla.org"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-83/", "tags": ["Vendor Advisory"], "source": "security@mozilla.org"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-84/", "tags": ["Vendor Advisory"], "source": "security@mozilla.org"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-85/", "tags": ["Vendor Advisory"], "source": "security@mozilla.org"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-86/", "tags": ["Vendor Advisory"], "source": "security@mozilla.org"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-87/", "tags": ["Vendor Advisory"], "source": "security@mozilla.org"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-88/", "tags": ["Vendor Advisory"], "source": "security@mozilla.org"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "description": [{"lang": "en", "value": "CWE-416"}]}], "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."}], "lastModified": "2026-09-02T16:36:20.367", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "B84FE134-AC5B-4FF4-9F3C-704D92475BD1", "versionEndExcluding": "115.40.0"}, {"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "933C120C-6E83-48E4-8002-38E2C93D8E47", "versionEndExcluding": "140.15.0", "versionStartIncluding": "116.0"}, {"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "BAC56AB7-FB63-4A76-BFBD-4C0122F2A93C", "versionEndExcluding": "153.2.0", "versionStartIncluding": "141.0.0"}, {"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "56769A1A-4A97-4814-8963-24B7AFD7E44F", "versionEndExcluding": "155.0.0", "versionStartIncluding": "154.0.0"}, {"criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "EC44CB46-89FD-40DC-92D1-F865A0521D06", "versionEndExcluding": "140.15.0"}, {"criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "B217A29A-45B5-407C-9B4B-96CF6EB0838E", "versionEndExcluding": "153.2.0", "versionStartIncluding": "141.0"}, {"criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "C6AB910B-074A-42F7-A3C7-B7E822011D92", "versionEndExcluding": "155.0", "versionStartIncluding": "154.0"}], "operator": "OR"}]}], "sourceIdentifier": "security@mozilla.org"}