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: 0.2%, top 95% 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: 0.2%CVSS: 4.8Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

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
4.8MEDIUMmedium confidence
EG Risk
38
EG Risk 38/100

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%
EPSS PROB
0.2%
EPSS %ILE
4th
KEV
Not listed

Published

June 25, 2026

Last Modified

September 8, 2026

Advisory Details (3)

Auto-updated Aug 18, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit, github_release.
githubMentions a patch (unverified)🟡 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 rangeFix by version rangeDependents
lemur0.11.0 ... 1.9.1 (19 versions)
  • every version up to 1.9.2: fixed in 1.9.2
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 28× 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. 2026-10-10 20:00 UTCEPSS rescore
  2. 2026-10-09 20:07 UTCEPSS rescore
  3. 2026-10-08 17:12 UTCEPSS rescore
  4. 2026-10-07 23:48 UTCEPSS rescore
  5. 2026-10-06 15:18 UTCEPSS rescore
  6. 2026-10-05 17:43 UTCEPSS rescore
  7. 2026-10-04 23:22 UTCEPSS rescore
  8. 2026-10-03 14:26 UTCEPSS rescore
  9. 2026-10-02 17:56 UTCEPSS rescore
  10. 2026-10-01 19:50 UTCEPSS rescore
  11. 2026-09-30 15:03 UTCEPSS rescore
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  13. 2026-09-28 13:51 UTCEPSS rescore
  14. 2026-09-27 13:48 UTCEPSS rescore
  15. 2026-09-26 15:59 UTCEPSS rescore
  16. 2026-09-24 14:04 UTCEPSS rescore
  17. 2026-09-23 17:54 UTCEPSS rescore
  18. 2026-09-23 08:25 UTCEG score recompute
  19. 2026-09-20 20:16 UTCEPSS rescore
  20. 2026-09-18 19:28 UTCEPSS rescore
  21. 2026-09-18 07:19 UTCEG score recompute
  22. 2026-09-17 19:31 UTCEPSS rescore
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  1. 2026-09-14 01:16 UTCEG score recompute
  2. 2026-09-13 16:47 UTCEPSS rescore
  3. 2026-09-12 15:41 UTCEG score recompute
  4. 2026-09-10 09:35 UTCEPSS rescore
  5. 2026-09-08 22:59 UTCEG score recompute
  6. 2026-09-08 22:01 UTCEPSS rescore
  7. 2026-09-07 16:01 UTCEPSS rescore
  8. 2026-09-06 13:47 UTCEPSS rescore
  9. 2026-09-04 05:06 UTCEPSS rescore
  10. 2026-09-02 14:12 UTCEPSS rescore
  11. 2026-09-01 13:54 UTCEPSS rescore
  12. 2026-09-01 04:40 UTCEPSS rescore
  13. 2026-08-30 19:28 UTCEG score recompute
  14. 2026-08-30 19:17 UTCEPSS rescore
  15. 2026-08-30 01:22 UTCEPSS rescore
  16. 2026-08-28 21:41 UTCEPSS rescore
  17. 2026-08-27 23:16 UTCEG score recompute
  18. 2026-08-27 14:25 UTCEPSS rescore
  19. 2026-08-26 14:46 UTCEPSS rescore
  20. 2026-08-25 13:49 UTCEPSS rescore
  21. 2026-08-24 21:50 UTCEG score recompute
  22. 2026-08-23 13:41 UTCEG score recompute
  23. 2026-08-23 00:19 UTCEPSS rescore
  24. 2026-08-22 11:28 UTCEG score recompute
  25. 2026-08-21 23:49 UTCEPSS rescore
  26. 2026-08-21 09:15 UTCEG score recompute
  27. 2026-08-20 22:55 UTCEPSS rescore
  28. 2026-08-20 07:01 UTCEG score recompute
  29. 2026-08-19 17:04 UTCEPSS rescore
  30. 2026-08-18 20:25 UTCEG score recompute
  31. 2026-08-18 19:45 UTCEG score recompute
  32. 2026-08-18 19:25 UTCEG score recompute
  33. 2026-07-31 02:54 UTCEG score recompute
  34. 2026-07-26 14:54 UTCEG score recompute
  35. 2026-07-23 03:20 UTCEG score recompute
  36. 2026-06-25 22:46 UTCEG score recompute

Related CVEs(same product + 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 on June 25, 2026, with the most recent update on September 8, 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 0.2% probability of exploitation in the next 30 days (4th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55165?
CVE-2026-55165 has a CVSS base score of 4.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55165?
A fix for CVE-2026-55165 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55165 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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