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{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*", "matchCriteriaId": "15AF037C-5C86-48EB-B1DE-3AC100A34596", "versionEndExcluding": "140.10.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*", "matchCriteriaId": "67B01D49-66FA-4C76-9EB4-2B8CD61FBEB2", "versionEndExcluding": "150.0", "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 File Handling component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10."}], "id": "CVE-2026-6763", "lastModified": "2026-04-22T17:38:00.877", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 2.5, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}, "published": "2026-04-21T13:16:22.227", "references": [{"source": "security@mozilla.org", "tags": ["Permissions Required"], "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2021666"}, {"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-693"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"bugzilla": {"description": "firefox: Mitigation bypass in the File Handling component", "id": "2460101", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2460101"}, "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-66", "details": ["A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:\nMitigation bypass in the File Handling component"], "name": "CVE-2026-6763", "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": "2026-04-21T12:40:57Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-6763\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-6763\nhttps://www.mozilla.org/security/advisories/mfsa2026-32/#CVE-2026-6763"], "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": "2026-04-22T15:10:25.796417+00:00", "value": {"mitigation_remediation": ["Apply the latest Firefox or Firefox ESR update (version\u202f150 or newer, ESR\u202f140.10 or newer).", "Apply the latest Thunderbird or Thunderbird ESR update (version\u202f150 or newer, ESR\u202f140.10 or newer).", "Temporarily disable or uninstall any extensions or add-ons that interact with the file handling component until the update is applied."], "summary": {"action": "Patch", "impact": "Mitigation Bypass"}, "threat_synthesis": {"affected_systems": "Both Mozilla Firefox and Mozilla Thunderbird are affected. In Firefox, all versions before 150 and ESR releases prior to 140.10 contain the flaw; Thunderbird is vulnerable in all versions before 150 and ESR releases before 140.10. The issue applies to every build of these products that does not include the state\u2011of\u2011the\u2011art mitigation fix.", "description_and_impact": "The vulnerability lies in the File Handling component of Mozilla products and is classified as CWE-66 (Configuration and Deployment Management) and CWE-693 (Protection Mechanism Failure). It enables malicious actors to bypass implemented mitigations that enforce safe file handling, potentially altering program behaviour. The impact constitutes a mitigation bypass that may facilitate exploitation of other weaknesses.", "risk_and_exploitability": "The CVSS score of 6.5 indicates a moderate severity. No EPSS score is available, and the vulnerability is not listed in the CISA KEV catalog. The risk depends on an adversary\u2019s ability to supply files or code that reach the vulnerable component. While direct exploitation may require local or trusted code execution, a bypass of file\u2011handling mitigations could lower the bar for other attacks that rely on the same component. The vulnerability was officially fixed in Firefox 150 / ESR\u202f140.10 and Thunderbird 150 / ESR\u202f140.10."}}}}, "created": "2026-04-21T17:00:11.951565+00:00", "updated": "2026-04-22T15:15:16.424010+00:00", "vendors": ["mozilla", "mozilla$PRODUCT$firefox"]}