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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": "Uninitialized memory in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10."}], "id": "CVE-2026-6751", "lastModified": "2026-04-22T16:08:53.690", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "LOW", "baseScore": 7.3, "baseSeverity": "HIGH", "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:L", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.4, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}, "published": "2026-04-21T13:16:21.163", "references": [{"source": "security@mozilla.org", "tags": ["Permissions Required"], "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2025883"}, {"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-457"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"bugzilla": {"description": "firefox: Uninitialized memory in the Audio/Video: Web Codecs component", "id": "2460109", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2460109"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-824", "details": ["A flaw was found in Firefox. The Mozilla Foundation's Security Advisory describes the following issue:\nUninitialized memory in the Audio/Video: Web Codecs component"], "name": "CVE-2026-6751", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "rhel10/firefox-flatpak", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "firefox", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-04-21T12:40:48Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-6751\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-6751\nhttps://www.mozilla.org/security/advisories/mfsa2026-30/#CVE-2026-6751\nhttps://www.mozilla.org/security/advisories/mfsa2026-32/#CVE-2026-6751"], "statement": "Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.", "threat_severity": "Important"}

{"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": "2026-04-22T13:46:15.180792+00:00", "value": {"mitigation_remediation": ["Upgrade Mozilla Firefox to version 150 or later, or to Firefox ESR 140.10 or later, when available.", "Upgrade Mozilla Thunderbird to version 150 or later, or to Thunderbird ESR 140.10 or later, when available.", "If upgrading is not immediately possible, disable the Web Codecs feature by setting the preference \"media.webcodecs.enabled\" to false in about:config or via policy.", "Ensure that automatic updates are enabled so that any further security updates for Firefox or Thunderbird are installed promptly, and monitor Mozilla advisories for any subsequent patches or workarounds."], "summary": {"action": "Apply Patch", "impact": "Information Disclosure"}, "threat_synthesis": {"affected_systems": "The affected vendor is Mozilla, specifically the Firefox browser and Thunderbird mail client. The flaw exists in all versions prior to Firefox 150 and Firefox ESR 140.10, as well as Thunderbird versions before 150 and Thunderbird ESR 140.10, where the Web Codecs API could access memory that was never initialized.", "description_and_impact": "This vulnerability involves uninitialized memory access within the Audio/Video: Web Codecs component of Mozilla products, classified as CWE-457 and CWE-824. The flaw permits the reading of memory that has not been initialized, potentially exposing sensitive data and causing application instability. The issue has been mitigated in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.", "risk_and_exploitability": "The CVSS score of 7.3 indicates a high potential impact. The EPSS score is not available, and the vulnerability is not listed in CISA KEV. Because the flaw occurs in the Web Codecs API, it is most likely exploitable through malicious web content that leverages the codec functionality. No confirmed exploits exist, but the potential for data leakage warrants patching before any exploit is discovered. The attack vector is likely remote, delivered via web pages, but the specific feasibility remains uncertain."}}}}, "created": "2026-04-21T16:45:15.078565+00:00", "updated": "2026-04-22T14:00:18.226793+00:00", "vendors": ["mozilla", "mozilla$PRODUCT$firefox"]}