Memory safety bugs present in Firefox 139 and Thunderbird 139. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 140 and Thunderbird 140.

zetlyn/cve-nvd vulnerability cve CVE-2025-6436 cpe cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* cpe cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* known 2025-06-24

https://nvd.nist.gov/vuln/detail/CVE-2025-6436

Properties

cvss	8.1 receipt Source NVD Its words `8.1` Read by `field:cve.metrics.cvssMetricV31[].cvssData.baseScore` Said since 2026-10-02 12:00 UTC Last answered 2026-10-05 12:24 UTC Original open at the source What the source handed over { "cve": { "affected": [ { "affectedData": [ { "product": "Firefox", "vendor": "Mozilla", "versions": [ { "lessThanOrEqual": "", "status": "unaffected", "version": "140", "versionType": "rpm" } ] }, { "product": "Thunderbird", "vendor": "Mozilla", "versions": [ { "lessThanOrEqual": "", "status": "unaffected", "version": "140", "versionType": "rpm" } ] } ], "source": "security@mozilla.org" } ], "configurations": [ { "nodes": [ { "cpeMatch": [ { "criteria": "cpe:2.3:a:mozilla:firefox::::::::", "matchCriteriaId": "6BD96DBF-567C-4E36-844D-B25A4E22CE40", "versionEndExcluding": "140.0", "vulnerable": true }, { "criteria": "cpe:2.3:a:mozilla:thunderbird::::::::", "matchCriteriaId": "EE6112E1-F482-4916-BA5E-68868793540F", "versionEndExcluding": "140.0", "vulnerable": true } ], "negate": false, "operator": "OR" } ] } ], "cveTags": [], "descriptions": [ { "lang": "en", "value": "Memory safety bugs present in Firefox 139 and Thunderbird 139. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 140 and Thunderbird 140." }, { "lang": "es", "value": "Errores de seguridad de memoria presentes en Firefox 139 y Thunderbird 139. Algunos de estos errores mostraron evidencia de corrupción de memoria y presumimos que, con suficiente esfuerzo, algunos de ellos podrían haberse explotado para ejecutar código arbitrario. Esta vulnerabilidad afecta a Firefox anterior a la versión 140." } ], "id": "CVE-2025-6436", "lastModified": "2026-09-30T18:10:00.190", "metrics": { "cvssMetricV31": [ { "cvssData": { "attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1" }, "exploitabilityScore": 2.2, "impactScore": 5.9, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary" } ], "ssvcV203": [ { "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": { "id": "CVE-2025-6436", "options": [ { "exploitation": "none" }, { "automatable": "yes" }, { "technicalImpact": "total" } ], "role": "CISA Coordinator", "timestamp": "2025-06-25T03:55:43.309265Z", "version": "2.0.3" } } ] }, "published": "2025-06-24T13:15:24.677", "references": [ { "source": "security@mozilla.org", "tags": [ "Permissions Required" ], "url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=1941377%2C1960948%2C1966187%2C1966505%2C1970764%2C1942930" }, { "source": "security@mozilla.org", "tags": [ "Vendor Advisory" ], "url": "https://www.mozilla.org/security/advisories/mfsa2025-51/" }, { "source": "security@mozilla.org", "tags": [ "Vendor Advisory" ], "url": "https://www.mozilla.org/security/advisories/mfsa2025-54/" } ], "sourceIdentifier": "security@mozilla.org", "vulnStatus": "Modified", "weaknesses": [ { "description": [ { "lang": "en", "value": "CWE-119" } ], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary" } ] } }
product	Firefox receipt Source NVD Its words `Firefox` Read by `field:cve.affected[].affectedData[].product` Said since 2026-10-02 12:00 UTC Last answered 2026-10-05 12:24 UTC Original open at the source What the source handed over { "cve": { "affected": [ { "affectedData": [ { "product": "Firefox", "vendor": "Mozilla", "versions": [ { "lessThanOrEqual": "", "status": "unaffected", "version": "140", "versionType": "rpm" } ] }, { "product": "Thunderbird", "vendor": "Mozilla", "versions": [ { "lessThanOrEqual": "", "status": "unaffected", "version": "140", "versionType": "rpm" } ] } ], "source": "security@mozilla.org" } ], "configurations": [ { "nodes": [ { "cpeMatch": [ { "criteria": "cpe:2.3:a:mozilla:firefox::::::::", "matchCriteriaId": "6BD96DBF-567C-4E36-844D-B25A4E22CE40", "versionEndExcluding": "140.0", "vulnerable": true }, { "criteria": "cpe:2.3:a:mozilla:thunderbird::::::::", "matchCriteriaId": "EE6112E1-F482-4916-BA5E-68868793540F", "versionEndExcluding": "140.0", "vulnerable": true } ], "negate": false, "operator": "OR" } ] } ], "cveTags": [], "descriptions": [ { "lang": "en", "value": "Memory safety bugs present in Firefox 139 and Thunderbird 139. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 140 and Thunderbird 140." }, { "lang": "es", "value": "Errores de seguridad de memoria presentes en Firefox 139 y Thunderbird 139. Algunos de estos errores mostraron evidencia de corrupción de memoria y presumimos que, con suficiente esfuerzo, algunos de ellos podrían haberse explotado para ejecutar código arbitrario. Esta vulnerabilidad afecta a Firefox anterior a la versión 140." } ], "id": "CVE-2025-6436", "lastModified": "2026-09-30T18:10:00.190", "metrics": { "cvssMetricV31": [ { "cvssData": { "attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1" }, "exploitabilityScore": 2.2, "impactScore": 5.9, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary" } ], "ssvcV203": [ { "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": { "id": "CVE-2025-6436", "options": [ { "exploitation": "none" }, { "automatable": "yes" }, { "technicalImpact": "total" } ], "role": "CISA Coordinator", "timestamp": "2025-06-25T03:55:43.309265Z", "version": "2.0.3" } } ] }, "published": "2025-06-24T13:15:24.677", "references": [ { "source": "security@mozilla.org", "tags": [ "Permissions Required" ], "url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=1941377%2C1960948%2C1966187%2C1966505%2C1970764%2C1942930" }, { "source": "security@mozilla.org", "tags": [ "Vendor Advisory" ], "url": "https://www.mozilla.org/security/advisories/mfsa2025-51/" }, { "source": "security@mozilla.org", "tags": [ "Vendor Advisory" ], "url": "https://www.mozilla.org/security/advisories/mfsa2025-54/" } ], "sourceIdentifier": "security@mozilla.org", "vulnStatus": "Modified", "weaknesses": [ { "description": [ { "lang": "en", "value": "CWE-119" } ], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary" } ] } }
status	Modified receipt Source NVD Its words `Modified` Read by `field:cve.vulnStatus` Said since 2026-10-02 12:00 UTC Last answered 2026-10-05 12:24 UTC Original open at the source What the source handed over { "cve": { "affected": [ { "affectedData": [ { "product": "Firefox", "vendor": "Mozilla", "versions": [ { "lessThanOrEqual": "", "status": "unaffected", "version": "140", "versionType": "rpm" } ] }, { "product": "Thunderbird", "vendor": "Mozilla", "versions": [ { "lessThanOrEqual": "", "status": "unaffected", "version": "140", "versionType": "rpm" } ] } ], "source": "security@mozilla.org" } ], "configurations": [ { "nodes": [ { "cpeMatch": [ { "criteria": "cpe:2.3:a:mozilla:firefox::::::::", "matchCriteriaId": "6BD96DBF-567C-4E36-844D-B25A4E22CE40", "versionEndExcluding": "140.0", "vulnerable": true }, { "criteria": "cpe:2.3:a:mozilla:thunderbird::::::::", "matchCriteriaId": "EE6112E1-F482-4916-BA5E-68868793540F", "versionEndExcluding": "140.0", "vulnerable": true } ], "negate": false, "operator": "OR" } ] } ], "cveTags": [], "descriptions": [ { "lang": "en", "value": "Memory safety bugs present in Firefox 139 and Thunderbird 139. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 140 and Thunderbird 140." }, { "lang": "es", "value": "Errores de seguridad de memoria presentes en Firefox 139 y Thunderbird 139. Algunos de estos errores mostraron evidencia de corrupción de memoria y presumimos que, con suficiente esfuerzo, algunos de ellos podrían haberse explotado para ejecutar código arbitrario. Esta vulnerabilidad afecta a Firefox anterior a la versión 140." } ], "id": "CVE-2025-6436", "lastModified": "2026-09-30T18:10:00.190", "metrics": { "cvssMetricV31": [ { "cvssData": { "attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1" }, "exploitabilityScore": 2.2, "impactScore": 5.9, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary" } ], "ssvcV203": [ { "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": { "id": "CVE-2025-6436", "options": [ { "exploitation": "none" }, { "automatable": "yes" }, { "technicalImpact": "total" } ], "role": "CISA Coordinator", "timestamp": "2025-06-25T03:55:43.309265Z", "version": "2.0.3" } } ] }, "published": "2025-06-24T13:15:24.677", "references": [ { "source": "security@mozilla.org", "tags": [ "Permissions Required" ], "url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=1941377%2C1960948%2C1966187%2C1966505%2C1970764%2C1942930" }, { "source": "security@mozilla.org", "tags": [ "Vendor Advisory" ], "url": "https://www.mozilla.org/security/advisories/mfsa2025-51/" }, { "source": "security@mozilla.org", "tags": [ "Vendor Advisory" ], "url": "https://www.mozilla.org/security/advisories/mfsa2025-54/" } ], "sourceIdentifier": "security@mozilla.org", "vulnStatus": "Modified", "weaknesses": [ { "description": [ { "lang": "en", "value": "CWE-119" } ], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary" } ] } }
vendor	Mozilla receipt Source NVD Its words `Mozilla` Read by `field:cve.affected[].affectedData[].vendor` Said since 2026-10-02 12:00 UTC Last answered 2026-10-05 12:24 UTC Original open at the source What the source handed over { "cve": { "affected": [ { "affectedData": [ { "product": "Firefox", "vendor": "Mozilla", "versions": [ { "lessThanOrEqual": "", "status": "unaffected", "version": "140", "versionType": "rpm" } ] }, { "product": "Thunderbird", "vendor": "Mozilla", "versions": [ { "lessThanOrEqual": "", "status": "unaffected", "version": "140", "versionType": "rpm" } ] } ], "source": "security@mozilla.org" } ], "configurations": [ { "nodes": [ { "cpeMatch": [ { "criteria": "cpe:2.3:a:mozilla:firefox::::::::", "matchCriteriaId": "6BD96DBF-567C-4E36-844D-B25A4E22CE40", "versionEndExcluding": "140.0", "vulnerable": true }, { "criteria": "cpe:2.3:a:mozilla:thunderbird::::::::", "matchCriteriaId": "EE6112E1-F482-4916-BA5E-68868793540F", "versionEndExcluding": "140.0", "vulnerable": true } ], "negate": false, "operator": "OR" } ] } ], "cveTags": [], "descriptions": [ { "lang": "en", "value": "Memory safety bugs present in Firefox 139 and Thunderbird 139. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 140 and Thunderbird 140." }, { "lang": "es", "value": "Errores de seguridad de memoria presentes en Firefox 139 y Thunderbird 139. Algunos de estos errores mostraron evidencia de corrupción de memoria y presumimos que, con suficiente esfuerzo, algunos de ellos podrían haberse explotado para ejecutar código arbitrario. Esta vulnerabilidad afecta a Firefox anterior a la versión 140." } ], "id": "CVE-2025-6436", "lastModified": "2026-09-30T18:10:00.190", "metrics": { "cvssMetricV31": [ { "cvssData": { "attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1" }, "exploitabilityScore": 2.2, "impactScore": 5.9, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary" } ], "ssvcV203": [ { "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": { "id": "CVE-2025-6436", "options": [ { "exploitation": "none" }, { "automatable": "yes" }, { "technicalImpact": "total" } ], "role": "CISA Coordinator", "timestamp": "2025-06-25T03:55:43.309265Z", "version": "2.0.3" } } ] }, "published": "2025-06-24T13:15:24.677", "references": [ { "source": "security@mozilla.org", "tags": [ "Permissions Required" ], "url": "https://bugzilla.mozilla.org/buglist.cgi?bug_id=1941377%2C1960948%2C1966187%2C1966505%2C1970764%2C1942930" }, { "source": "security@mozilla.org", "tags": [ "Vendor Advisory" ], "url": "https://www.mozilla.org/security/advisories/mfsa2025-51/" }, { "source": "security@mozilla.org", "tags": [ "Vendor Advisory" ], "url": "https://www.mozilla.org/security/advisories/mfsa2025-54/" } ], "sourceIdentifier": "security@mozilla.org", "vulnStatus": "Modified", "weaknesses": [ { "description": [ { "lang": "en", "value": "CWE-119" } ], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary" } ] } }

Text

Memory safety bugs present in Firefox 139 and Thunderbird 139. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 140 and Thunderbird 140. Errores de seguridad de memoria presentes en Firefox 139 y Thunderbird 139. Algunos de estos errores mostraron evidencia de corrupción de memoria y presumimos que, con suficiente esfuerzo, algunos de ellos podrían haberse explotado para ejecutar código arbitrario. Esta vulnerabilidad afecta a Firefox anterior a la versión 140.