CVE-2026-84640

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-84640", "assignerOrgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe", "state": "PUBLISHED", "assignerShortName": "mozilla", "dateReserved": "2026-09-01T21:33:06.555Z", "datePublished": "2026-09-01T21:33:06.832Z", "dateUpdated": "2026-09-02T18:48:06.654Z"}, "containers": {"cna": {"affected": [{"product": "Thunderbird", "vendor": "Mozilla", "versions": [{"status": "unaffected", "version": "140.15", "lessThanOrEqual": "140.*", "versionType": "rpm"}, {"status": "unaffected", "version": "153.2", "lessThanOrEqual": "153.*", "versionType": "rpm"}, {"status": "unaffected", "version": "155", "lessThanOrEqual": "*", "versionType": "rpm"}]}], "descriptions": [{"lang": "en", "value": "A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2."}]}], "title": "One byte overflow read in mail parser", "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2063964"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-86/"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-87/"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-88/"}], "credits": [{"lang": "en", "value": "Ramesh Adhikari, Dr. Faruk Kazi (CoE-CNDS Lab, VJTI, Mumbai, India)"}], "providerMetadata": {"orgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe", "shortName": "mozilla", "dateUpdated": "2026-09-01T21:44:15.623Z"}}, "adp": [{"problemTypes": [{"descriptions": [{"type": "CWE", "cweId": "CWE-126", "lang": "en", "description": "CWE-126 Buffer Over-read"}]}], "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}}, {"other": {"type": "ssvc", "content": {"timestamp": "2026-09-02T18:47:36.596726Z", "id": "CVE-2026-84640", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-02T18:48:06.654Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}}, {"other": {"type": "ssvc", "content": {"id": "CVE-2026-84640", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-02T18:47:36.596726Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-126", "description": "CWE-126 Buffer Over-read"}]}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-09-02T18:47:56.768Z"}}], "cna": {"title": "One byte overflow read in mail parser", "credits": [{"lang": "en", "value": "Ramesh Adhikari, Dr. Faruk Kazi (CoE-CNDS Lab, VJTI, Mumbai, India)"}], "affected": [{"vendor": "Mozilla", "product": "Thunderbird", "versions": [{"status": "unaffected", "version": "140.15", "versionType": "rpm", "lessThanOrEqual": "140.*"}, {"status": "unaffected", "version": "153.2", "versionType": "rpm", "lessThanOrEqual": "153.*"}, {"status": "unaffected", "version": "155", "versionType": "rpm", "lessThanOrEqual": "*"}]}], "references": [{"url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2063964"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-86/"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-87/"}, {"url": "https://www.mozilla.org/security/advisories/mfsa2026-88/"}], "descriptions": [{"lang": "en", "value": "A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.", "supportingMedia": [{"type": "text/html", "value": "A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.", "base64": false}]}], "providerMetadata": {"orgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe", "shortName": "mozilla", "dateUpdated": "2026-09-01T21:44:15.623Z"}}}, "cveMetadata": {"cveId": "CVE-2026-84640", "state": "PUBLISHED", "dateUpdated": "2026-09-02T18:48:06.654Z", "dateReserved": "2026-09-01T21:33:06.555Z", "assignerOrgId": "f16b083a-5664-49f3-a51e-8d479e5ed7fe", "datePublished": "2026-09-01T21:33:06.832Z", "assignerShortName": "mozilla"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"product": "Thunderbird", "vendor": "Mozilla", "versions": [{"lessThanOrEqual": "140.*", "status": "unaffected", "version": "140.15", "versionType": "rpm"}, {"lessThanOrEqual": "153.*", "status": "unaffected", "version": "153.2", "versionType": "rpm"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "155", "versionType": "rpm"}]}], "source": "security@mozilla.org"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*", "matchCriteriaId": "EC44CB46-89FD-40DC-92D1-F865A0521D06", "versionEndExcluding": "140.15.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*", "matchCriteriaId": "B217A29A-45B5-407C-9B4B-96CF6EB0838E", "versionEndExcluding": "153.2.0", "versionStartIncluding": "141.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*", "matchCriteriaId": "C6AB910B-074A-42F7-A3C7-B7E822011D92", "versionEndExcluding": "155.0", "versionStartIncluding": "154.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2."}], "id": "CVE-2026-84640", "lastModified": "2026-09-03T19:01:32.800", "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"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-84640", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-09-02T18:47:36.596726Z", "version": "2.0.3"}}]}, "published": "2026-09-01T22:17:19.800", "references": [{"source": "security@mozilla.org", "tags": ["Permissions Required"], "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=2063964"}, {"source": "security@mozilla.org", "tags": ["Vendor Advisory"], "url": "https://www.mozilla.org/security/advisories/mfsa2026-86/"}, {"source": "security@mozilla.org", "tags": ["Vendor Advisory"], "url": "https://www.mozilla.org/security/advisories/mfsa2026-87/"}, {"source": "security@mozilla.org", "tags": ["Vendor Advisory"], "url": "https://www.mozilla.org/security/advisories/mfsa2026-88/"}], "sourceIdentifier": "security@mozilla.org", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-126"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"bugzilla": {"description": "thunderbird: One byte overflow read in mail parser", "id": "2527116", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2527116"}, "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-125", "details": ["A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.", "A flaw was found in Thunderbird. A remote attacker could exploit this vulnerability by sending a maliciously constructed mail header. This could lead to a one-byte read past the end of a buffer, potentially resulting in information disclosure or other unpredictable behavior."], "name": "CVE-2026-84640", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "rhel10/thunderbird-flatpak", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "thunderbird", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-09-01T21:33:06Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-84640\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-84640\nhttps://www.mozilla.org/security/advisories/mfsa2026-87/#CVE-2026-84640"], "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": "[140.15,140.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[153.2,153.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[155,*]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Thunderbird", "source": "cna", "vendor": "Mozilla"}, "product": "thunderbird", "vendor": "mozilla"}], "created": "2026-09-01T23:45:17.140492+00:00", "updated": "2026-09-21T06:30:09.141995+00:00", "vendors": ["mozilla", "mozilla$PRODUCT$thunderbird"]}