CVE-2026-55165

MEDIUMPre-NVD 4.84.8—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 98% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
4.8EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.8Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
4.8
EG Score
4.8(medium)
EG Risk
38(Track)
EG Risk 38/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity48% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
3%
KEV
Not listed

Published

June 25, 2026

Last Modified

August 18, 2026

Advisory Details (3)

Auto-updated Aug 18, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit, github_release.
github Patch Available🟡 PoC Available

Lemur 1.9.0: JWT verifier trusts attacker-supplied alg from token header — defense-in-depth gap; chain-dependent ATO with secret disclosure · Advisory · Netflix/lemur · GitHub

https://github.com/Netflix/lemur/security/advisories/GHSA-r9gp-7f88-9r54
github_release Patch Available

v1.9.2

Patch available: Netflix/lemur v1.9.2

https://github.com/Netflix/lemur/releases/tag/v1.9.2
github_commit Patch Available

commit 89898e665bee (Netflix/lemur)

Patch available: Netflix/lemur v1.9.2 (contains commit 89898e665bee)

https://github.com/Netflix/lemur/commit/89898e665beed044cf7bd5927dfaa484e55bf242

Vendor Advisories for CVE-2026-55165(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
lemur0.11.0 ... 1.9.1 (19 versions)1.9.2—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 15× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-26 14:46 UTCEPSS rescore
  2. 2026-08-25 13:49 UTCEPSS rescore
  3. 2026-08-24 21:50 UTCEG score recompute
  4. 2026-08-23 13:41 UTCEG score recompute
  5. 2026-08-23 00:19 UTCEPSS rescore
  6. 2026-08-22 11:28 UTCEG score recompute
  7. 2026-08-21 23:49 UTCEPSS rescore
  8. 2026-08-21 09:15 UTCEG score recompute
  9. 2026-08-20 22:55 UTCEPSS rescore
  10. 2026-08-20 07:01 UTCEG score recompute
  11. 2026-08-19 17:04 UTCEPSS rescore
  12. 2026-08-18 20:25 UTCEG score recompute
  13. 2026-08-18 19:45 UTCEG score recompute
  14. 2026-08-18 19:25 UTCEG score recompute
  15. 2026-07-31 02:54 UTCEG score recompute
  16. 2026-07-26 14:54 UTCEG score recompute
  17. 2026-07-23 03:20 UTCEG score recompute
  18. 2026-06-25 22:46 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55165?
CVE-2026-55165 is a medium vulnerability published on June 25, 2026. Lemur manages TLS certificate creation. Prior to 1.9.2, the JWT verifier in lemur/auth/service.py:130-137 used fetchtokenheader to read headerdata["alg"] from an unverified token and passed that attacker-controlled value to decodewithmultiplesecrets. PyJWT 2.x rejects alg=none with the configured…
When was CVE-2026-55165 disclosed?
CVE-2026-55165 was first published in the National Vulnerability Database on June 25, 2026, with the most recent update on August 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55165 actively exploited?
CVE-2026-55165 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 97.5% of all scored CVEs.
What is the CVSS score of CVE-2026-55165?
CVE-2026-55165 has a CVSS v3 base score of 4.8 (NVD).
How do I remediate CVE-2026-55165?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55165, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-55165

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