{"apiVersion":"1.0","identifier":"CVE-2026-55165","description":"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.","publishedAt":"2026-08-18T19:16:58","lastModifiedAt":"2026-08-18T20:17:18","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-55165","cvssScore":4.8,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","epssProbability":0.00126,"riskScore":0.49,"affectedProduct":"Lemur","affectedVersions":"<1.9.2","vulnerabilityType":"Web app","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-55165","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-55165","en":"https://www.redsauce.net/en/cves/CVE-2026-55165","fr":"https://www.redsauce.net/fr/cves/CVE-2026-55165","pt":"https://www.redsauce.net/pt/cves/CVE-2026-55165","de":"https://www.redsauce.net/de/cves/CVE-2026-55165","sk":"https://www.redsauce.net/sk/cves/CVE-2026-55165","el":"https://www.redsauce.net/el/cves/CVE-2026-55165"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-55165"}}