{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-74987", "assignerOrgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe", "state": "PUBLISHED", "assignerShortName": "mozilla", "dateReserved": "2026-08-17T11:59:22.495Z", "datePublished": "2026-08-18T12:23:34.847Z", "dateUpdated": "2026-08-18T18:55:24.240Z"}, "containers": {"cna": {"affected": [{"product": "Firefox", "vendor": "Mozilla", "versions": [{"status": "unaffected", "version": "140.14", "lessThanOrEqual": "140.*", "versionType": "rpm"}, {"status": "unaffected", "version": "153.1", "lessThanOrEqual": "153.*", "versionType": "rpm"}, {"status": "unaffected", "version": "154", "lessThanOrEqual": "*", "versionType": "rpm"}]}, {"product": "Thunderbird", "vendor": "Mozilla", "versions": [{"status": "unaffected", "version": "140.14", "lessThanOrEqual": "140.*", "versionType": "rpm"}, {"status": "unaffected", "version": "153.1", "lessThanOrEqual": "153.*", "versionType": "rpm"}, {"status": "unaffected", "version": "154", "lessThanOrEqual": "*", "versionType": "rpm"}]}], "descriptions": [{"lang": "en", "value": "Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1."}]}], "title": "Internally found bugs fixed in Thunderbird ESR 140.14, Thunderbird ESR 153.1 and Thunderbird 154", "references": [{"url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=1500946%2C1788109%2C2045379%2C2045380%2C2049339%2C2049393%2C2053580%2C2054662%2C2054665%2C2054673%2C2054785%2C2058645", "name": "Moderate Severity internally found bugs fixed in Thunderbird ESR 140.14, Thunderbird ESR 153.1 and Thunderbird 154"}, {"url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=2048797%2C2050536%2C2053272%2C2053579%2C2057115%2C2057116%2C2057130%2C2057991%2C2057995%2C2058002%2C2058008%2C2058032%2C2058102%2C2058667", "name": "High Severity internally found bugs fixed in Thunderbird ESR 140.14, Thunderbird ESR 153.1 and Thunderbird 154"}, {"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2059424", "name": "Low Severity internally found bugs fixed in Thunderbird ESR 140.14, Thunderbird ESR 153.1 and Thunderbird 154"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-74/"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-76/"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-77/"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-78/"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-79/"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-80/"}], "credits": [{"lang": "en", "value": "Nicolas Silva, Tom Ritter and the Mozilla Fuzzing Team"}], "providerMetadata": {"orgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe", "shortName": "mozilla", "dateUpdated": "2026-08-18T18:55:24.240Z"}}}}

{}

{"affected": [{"affectedData": [{"product": "Firefox", "vendor": "Mozilla", "versions": [{"lessThanOrEqual": "140.*", "status": "unaffected", "version": "140.14", "versionType": "rpm"}, {"lessThanOrEqual": "153.*", "status": "unaffected", "version": "153.1", "versionType": "rpm"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "154", "versionType": "rpm"}]}, {"product": "Thunderbird", "vendor": "Mozilla", "versions": [{"lessThanOrEqual": "140.*", "status": "unaffected", "version": "140.14", "versionType": "rpm"}, {"lessThanOrEqual": "153.*", "status": "unaffected", "version": "153.1", "versionType": "rpm"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "154", "versionType": "rpm"}]}], "source": "security@mozilla.org"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1."}], "id": "CVE-2026-74987", "lastModified": "2026-08-18T19:17:17.087", "metrics": {}, "published": "2026-08-18T13:17:40.560", "references": [{"source": "security@mozilla.org", "url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=1500946%2C1788109%2C2045379%2C2045380%2C2049339%2C2049393%2C2053580%2C2054662%2C2054665%2C2054673%2C2054785%2C2058645"}, {"source": "security@mozilla.org", "url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=2048797%2C2050536%2C2053272%2C2053579%2C2057115%2C2057116%2C2057130%2C2057991%2C2057995%2C2058002%2C2058008%2C2058032%2C2058102%2C2058667"}, {"source": "security@mozilla.org", "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2059424"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2026-74/"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2026-76/"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2026-77/"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2026-78/"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2026-79/"}, {"source": "security@mozilla.org", "url": "https://www.mozilla.org/security/advisories/mfsa2026-80/"}], "sourceIdentifier": "security@mozilla.org", "vulnStatus": "Undergoing Analysis"}

{}

{"affected": [{"configurations": [{"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[140.14,141.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[153.1,154.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[154,*]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Firefox", "source": "cna", "vendor": "Mozilla"}, "product": "firefox", "vendor": "mozilla"}], "created": "2026-08-18T13:45:04.983389+00:00", "updated": "2026-08-18T21:30:04.794754+00:00", "vendors": ["mozilla", "mozilla$PRODUCT$firefox"]}