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{"cveTags": [], "descriptions": [{"lang": "en", "value": "Incorrect boundary conditions in the Libraries component in NSS. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10."}], "id": "CVE-2026-6766", "lastModified": "2026-04-22T00:16:32.930", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}, "published": "2026-04-21T13:16:22.493", "references": [{"source": "security@mozilla.org", "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2023207"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2026-30/"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2026-32/"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2026-33/"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2026-34/"}], "sourceIdentifier": "security@mozilla.org", "vulnStatus": "Undergoing Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-754"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[140.10,141.0.0)"}}, {"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": "2026-04-22T05:45:02.840447+00:00", "value": {"mitigation_remediation": ["Update Mozilla Firefox to version 150, or Firefox ESR 140.10, or any later release that incorporates the NSS boundary fix.", "Restart the browser to ensure the updated NSS libraries are loaded.", "Monitor Mozilla security advisories and releases page for further updates or patches if an immediate upgrade is not feasible."], "summary": {"action": "Immediate Upgrade", "impact": "Potential memory corruption"}, "threat_synthesis": {"affected_systems": "All Mozilla Firefox releases prior to version 150 and Firefox ESR 140.10, as well as all Mozilla Thunderbird releases prior to version 150 and Thunderbird ESR 140.10, are affected.", "description_and_impact": "The vulnerability arises from incorrect boundary conditions within the NSS Libraries component of Mozilla Firefox. The flaw can corrupt memory when processing certain inputs, potentially leading to undefined behavior or other security consequences. The official description does not explicitly state that this could result in code execution or privilege escalation, so the exact impact remains uncertain.", "risk_and_exploitability": "Exploitation most likely involves malicious content or data handled by the browser, implying a remote attack vector from web pages or other user-supplied inputs. No EPSS score is available and the vulnerability is not listed in the CISA KEV catalog, but given the central role of NSS in cryptographic operations, the risk is high. The CVSS score of 7.5 indicates a high severity vulnerability. The absence of a known public exploit means the attack may still rely on crafted inputs, but the potential severity warrants immediate action."}}}}, "created": "2026-04-21T16:45:15.075421+00:00", "updated": "2026-04-22T05:45:09.828759+00:00", "vendors": ["mozilla", "mozilla$PRODUCT$firefox"]}