CVE-2026-6771

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{"affected": [{"affectedData": [{"product": "Firefox", "vendor": "Mozilla", "versions": [{"lessThanOrEqual": "140.*", "status": "unaffected", "version": "140.10", "versionType": "rpm"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "150", "versionType": "rpm"}]}, {"product": "Thunderbird", "vendor": "Mozilla", "versions": [{"lessThanOrEqual": "140.*", "status": "unaffected", "version": "140.10", "versionType": "rpm"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "150", "versionType": "rpm"}]}], "source": "security@mozilla.org"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*", "matchCriteriaId": "67B01D49-66FA-4C76-9EB4-2B8CD61FBEB2", "versionEndExcluding": "150.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*", "matchCriteriaId": "528443E0-C15A-4E70-9187-8E1BAAE84A42", "versionEndExcluding": "140.10.0", "versionStartIncluding": "140.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*", "matchCriteriaId": "6A8A3284-C06C-4591-9548-5324BD91C4FC", "versionEndExcluding": "140.10.0", "versionStartIncluding": "140.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10."}, {"lang": "es", "value": "Elusi\u00f3n de mitigaci\u00f3n en el DOM: Componente de seguridad. Esta vulnerabilidad fue corregida en Firefox 150, Firefox ESR 140.10, Thunderbird 150 y Thunderbird 140.10."}], "id": "CVE-2026-6771", "lastModified": "2026-10-26T22:10:00.163", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-6771", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-04-21T19:31:19.014643Z", "version": "2.0.3"}}]}, "published": "2026-04-21T13:16:22.927", "references": [{"source": "security@mozilla.org", "tags": ["Permissions Required"], "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2025067"}, {"source": "security@mozilla.org", "tags": ["Vendor Advisory"], "url": "https://www.mozilla.org/security/advisories/mfsa2026-30/"}, {"source": "security@mozilla.org", "tags": ["Vendor Advisory"], "url": "https://www.mozilla.org/security/advisories/mfsa2026-32/"}, {"source": "security@mozilla.org", "tags": ["Vendor Advisory"], "url": "https://www.mozilla.org/security/advisories/mfsa2026-33/"}, {"source": "security@mozilla.org", "tags": ["Vendor Advisory"], "url": "https://www.mozilla.org/security/advisories/mfsa2026-34/"}], "sourceIdentifier": "security@mozilla.org", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-288"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"bugzilla": {"description": "firefox: Mitigation bypass in the DOM: Security component", "id": "2460105", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2460105"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.1", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "status": "draft"}, "cwe": "CWE-358", "details": ["A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:\nMitigation bypass in the DOM: Security component"], "name": "CVE-2026-6771", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "rhel10/firefox-flatpak", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-04-21T12:41:03Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-6771\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-6771\nhttps://www.mozilla.org/security/advisories/mfsa2026-32/#CVE-2026-6771"], "statement": "Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.", "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[140.10,140.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[150,*]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Firefox", "source": "cna", "vendor": "Mozilla"}, "product": "firefox", "vendor": "mozilla"}], "analysis": {"en": {"generated_at": "2026-04-22T13:40:01.757691+00:00", "value": {"mitigation_remediation": ["Apply the official update for Mozilla Firefox (version 150 or newer or ESR 140.10 or newer).", "Apply the official update for Mozilla Thunderbird (version 150 or newer or ESR 140.10 or newer).", "If a patch cannot be applied immediately, disable or remove any extensions that alter the DOM or modify browser security settings to mitigate potential conflicts with the built-in mitigations."], "summary": {"action": "Patch immediately", "impact": "DOM security bypass"}, "threat_synthesis": {"affected_systems": "Mozilla Firefox versions earlier than 150 and any ESR releases prior to 140.10 are affected, as are Mozilla Thunderbird versions earlier than 150 and any ESR releases before 140.10. Users of these releases should apply the patched versions.", "description_and_impact": "The vulnerability, called \"Mitigation bypass in the DOM: Security component,\" removes enforcement of security checks applied to the Document Object Model in the browser. The defect was addressed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird ESR 140.10. The CVSS score of 9.8 indicates that an exploiter could achieve a highly damaging outcome, although the specific effects are not listed in the description and must be interpreted from the score alone.", "risk_and_exploitability": "The high CVSS rating identifies this flaw as severe, while the EPSS score is not available and the vulnerability is not listed in CISA's KEV catalog, suggesting that it is not currently widely exploited. The attack vector is likely client-side, as the flaw resides in the browser\u2019s DOM processing. In the absence of known exploitation, the risk is primarily theoretical but should be considered significant given the potential impact inferred from the CVSS score."}}}}, "created": "2026-04-21T16:45:15.073962+00:00", "updated": "2026-04-22T13:45:18.277611+00:00", "vendors": ["mozilla", "mozilla$PRODUCT$firefox"]}