{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-55165", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-06-16T15:13:28.165Z", "datePublished": "2026-08-18T18:49:59.538Z", "dateUpdated": "2026-08-18T19:35:55.129Z"}, "containers": {"cna": {"title": "Lemur : JWT verifier trusts attacker-supplied alg from token header \u2014 defense-in-depth gap; chain-dependent ATO with secret disclosure", "problemTypes": [{"descriptions": [{"cweId": "CWE-347", "lang": "en", "description": "CWE-347: Improper Verification of Cryptographic Signature", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 4.8, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/Netflix/lemur/security/advisories/GHSA-r9gp-7f88-9r54", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/Netflix/lemur/security/advisories/GHSA-r9gp-7f88-9r54"}, {"name": "https://github.com/Netflix/lemur/commit/89898e665beed044cf7bd5927dfaa484e55bf242", "tags": ["x_refsource_MISC"], "url": "https://github.com/Netflix/lemur/commit/89898e665beed044cf7bd5927dfaa484e55bf242"}, {"name": "https://github.com/Netflix/lemur/releases/tag/v1.9.2", "tags": ["x_refsource_MISC"], "url": "https://github.com/Netflix/lemur/releases/tag/v1.9.2"}], "affected": [{"vendor": "Netflix", "product": "lemur", "versions": [{"version": "< 1.9.2", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-08-18T18:49:59.538Z"}, "descriptions": [{"lang": "en", "value": "Lemur manages TLS certificate creation. Prior to 1.9.2, the JWT verifier in lemur/auth/service.py:130-137 used fetch_token_header to read header_data[\"alg\"] from an unverified token and passed that attacker-controlled value to decode_with_multiple_secrets. PyJWT 2.x rejects alg=none with the configured key, so the flaw is a defense-in-depth gap rather than a direct authentication bypass in the shipped configuration. The unpinned algorithm can become exploitable after an asymmetric-signing migration through algorithm confusion, and it weakens algorithm-based anomaly detection because the token chooses the recorded value. A separate disclosure of LEMUR_TOKEN_SECRET would also permit forged HS256 tokens, although that disclosure is an independent prerequisite. The fix introduces the server-controlled LEMUR_TOKEN_ALGORITHMS allowlist and defaults it to HS256. This issue is fixed in version 1.9.2."}], "source": {"advisory": "GHSA-r9gp-7f88-9r54", "discovery": "UNKNOWN"}}, "adp": [{"references": [{"url": "https://github.com/Netflix/lemur/security/advisories/GHSA-r9gp-7f88-9r54", "tags": ["exploit"]}], "metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-08-18T19:35:36.998493Z", "id": "CVE-2026-55165", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"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": "2026-08-18T19:35:55.129Z"}}]}}

{}

{"affected": [{"affectedData": [{"product": "lemur", "vendor": "Netflix", "versions": [{"status": "affected", "version": "< 1.9.2"}]}], "source": "security-advisories@github.com"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Lemur manages TLS certificate creation. Prior to 1.9.2, the JWT verifier in lemur/auth/service.py:130-137 used fetch_token_header to read header_data[\"alg\"] from an unverified token and passed that attacker-controlled value to decode_with_multiple_secrets. PyJWT 2.x rejects alg=none with the configured key, so the flaw is a defense-in-depth gap rather than a direct authentication bypass in the shipped configuration. The unpinned algorithm can become exploitable after an asymmetric-signing migration through algorithm confusion, and it weakens algorithm-based anomaly detection because the token chooses the recorded value. A separate disclosure of LEMUR_TOKEN_SECRET would also permit forged HS256 tokens, although that disclosure is an independent prerequisite. The fix introduces the server-controlled LEMUR_TOKEN_ALGORITHMS allowlist and defaults it to HS256. This issue is fixed in version 1.9.2."}], "id": "CVE-2026-55165", "lastModified": "2026-08-18T19:16:58.647", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 4.8, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.2, "impactScore": 2.5, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-08-18T19:16:58.647", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/Netflix/lemur/commit/89898e665beed044cf7bd5927dfaa484e55bf242"}, {"source": "security-advisories@github.com", "url": "https://github.com/Netflix/lemur/releases/tag/v1.9.2"}, {"source": "security-advisories@github.com", "url": "https://github.com/Netflix/lemur/security/advisories/GHSA-r9gp-7f88-9r54"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-347"}], "source": "security-advisories@github.com", "type": "Primary"}]}

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