{"api_version":"1","generated_at":"2026-07-23T12:27:30+00:00","cve":"CVE-2025-0239","urls":{"html":"https://cve.report/CVE-2025-0239","api":"https://cve.report/api/cve/CVE-2025-0239.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2025-0239","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-0239"},"summary":{"title":"Alt-Svc ALPN validation failure when redirected","description":"When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6.","state":"PUBLISHED","assigner":"mozilla","published_at":"2025-01-07 16:15:38","updated_at":"2026-04-13 15:16:32"},"problem_types":["CWE-295","CWE-295 CWE-295 Improper Certificate Validation"],"metrics":[{"version":"3.1","source":"ADP","type":"DECLARED","score":"4","severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","data":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"NONE","baseScore":4,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","version":"3.1"}},{"version":"3.1","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","type":"Secondary","score":"4","severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","baseScore":4,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"LOW","availabilityImpact":"NONE"}}],"references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1929156","name":"https://bugzilla.mozilla.org/show_bug.cgi?id=1929156","refsource":"security@mozilla.org","tags":["Issue Tracking","Permissions Required"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-02/","name":"https://www.mozilla.org/security/advisories/mfsa2025-02/","refsource":"security@mozilla.org","tags":["Vendor Advisory"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-01/","name":"https://www.mozilla.org/security/advisories/mfsa2025-01/","refsource":"security@mozilla.org","tags":["Vendor Advisory"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-05/","name":"https://www.mozilla.org/security/advisories/mfsa2025-05/","refsource":"security@mozilla.org","tags":["Vendor Advisory"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-04/","name":"https://www.mozilla.org/security/advisories/mfsa2025-04/","refsource":"security@mozilla.org","tags":["Vendor Advisory"],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00004.html","name":"https://lists.debian.org/debian-lts-announce/2025/01/msg00004.html","refsource":"af854a3a-2127-422b-91ae-364da2661108","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2025-0239","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-0239","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Mozilla","product":"Firefox","version":"unaffected 128.6 128.* rpm","platforms":[]},{"source":"CNA","vendor":"Mozilla","product":"Firefox","version":"unaffected 134 * rpm","platforms":[]},{"source":"CNA","vendor":"Mozilla","product":"Thunderbird","version":"unaffected 128.6 128.* rpm","platforms":[]},{"source":"CNA","vendor":"Mozilla","product":"Thunderbird","version":"unaffected 134 * rpm","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[{"source":"CNA","value":"Paul Gerste","lang":"en"}],"nvd_cpes":[{"cve_year":"2025","cve_id":"239","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"a","cpe4":"mozilla","cpe5":"firefox","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2025","cve_id":"239","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"a","cpe4":"mozilla","cpe5":"firefox","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"esr","cpe11":"*","cpe12":"*","cpe13":"*"},{"cve_year":"2025","cve_id":"239","vulnerable":"1","versionEndIncluding":"","cpe1":"cpe","cpe2":"2.3","cpe3":"a","cpe4":"mozilla","cpe5":"thunderbird","cpe6":"*","cpe7":"*","cpe8":"*","cpe9":"*","cpe10":"*","cpe11":"*","cpe12":"*","cpe13":"*"}],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"NONE","baseScore":4,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","version":"3.1"}},{"other":{"content":{"id":"CVE-2025-0239","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","timestamp":"2025-01-08T16:33:42.534195Z","version":"2.0.3"},"type":"ssvc"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-295","description":"CWE-295 Improper Certificate Validation","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2025-01-08T16:36:07.964Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"},{"providerMetadata":{"dateUpdated":"2025-11-03T22:33:39.114Z","orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE"},"references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00004.html"}],"title":"CVE Program Container"}],"cna":{"affected":[{"product":"Firefox","vendor":"Mozilla","versions":[{"lessThanOrEqual":"128.*","status":"unaffected","version":"128.6","versionType":"rpm"},{"lessThanOrEqual":"*","status":"unaffected","version":"134","versionType":"rpm"}]},{"product":"Thunderbird","vendor":"Mozilla","versions":[{"lessThanOrEqual":"128.*","status":"unaffected","version":"128.6","versionType":"rpm"},{"lessThanOrEqual":"*","status":"unaffected","version":"134","versionType":"rpm"}]}],"credits":[{"lang":"en","value":"Paul Gerste"}],"descriptions":[{"lang":"en","supportingMedia":[{"base64":false,"type":"text/html","value":"When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6."}],"value":"When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6."}],"providerMetadata":{"dateUpdated":"2026-04-13T14:30:01.233Z","orgId":"f16b083a-5664-49f3-a51e-8d479e5ed7fe","shortName":"mozilla"},"references":[{"url":"https://bugzilla.mozilla.org/show_bug.cgi?id=1929156"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-01/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-02/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-04/"},{"url":"https://www.mozilla.org/security/advisories/mfsa2025-05/"}],"title":"Alt-Svc ALPN validation failure when redirected"}},"cveMetadata":{"assignerOrgId":"f16b083a-5664-49f3-a51e-8d479e5ed7fe","assignerShortName":"mozilla","cveId":"CVE-2025-0239","datePublished":"2025-01-07T16:07:06.317Z","dateReserved":"2025-01-06T14:49:04.597Z","dateUpdated":"2026-04-13T14:30:01.233Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2025-01-07 16:15:38","lastModifiedDate":"2026-04-13 15:16:32","problem_types":["CWE-295","CWE-295 CWE-295 Improper Certificate Validation"],"metrics":{"cvssMetricV31":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","baseScore":4,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"LOW","availabilityImpact":"NONE"},"exploitabilityScore":2.5,"impactScore":1.4}]},"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*","versionEndExcluding":"128.6.0","matchCriteriaId":"AEBB7F43-496D-4A67-8E9E-EEE29913B6DE"},{"vulnerable":true,"criteria":"cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*","versionEndExcluding":"134.0","matchCriteriaId":"4FDCA935-A68D-404E-A749-CA3845C709F0"},{"vulnerable":true,"criteria":"cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*","versionEndExcluding":"128.6.0","matchCriteriaId":"C92D62DE-A681-4B9D-9640-D12D04392A1B"},{"vulnerable":true,"criteria":"cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*","versionStartIncluding":"129.0","versionEndExcluding":"134.0","matchCriteriaId":"A633E231-80F8-4A92-BA69-B9BE5BE45D00"}]}]}]},"legacy_mitre":{"record":{"CveYear":"2025","CveId":"239","Ordinal":"1","Title":"Alt-Svc ALPN validation failure when redirected","CVE":"CVE-2025-0239","Year":"2025"},"notes":[{"CveYear":"2025","CveId":"239","Ordinal":"1","NoteData":"When using Alt-Svc, ALPN did not properly validate certificates when the original server is redirecting to an insecure site. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6.","Type":"Description","Title":"Alt-Svc ALPN validation failure when redirected"}]}}}