CVE-2026-54338

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 79% 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
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: None knownExposed: 0

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

JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. Prior to 5.5.0, invalid input to form-based login authenticators can place an unbounded attacker-controlled username in failed-login logs, allowing an unauthenticated attacker to consume logging and storage resources. This issue is fixed in version 5.5.0.

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: 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
Severity53% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
21%
KEV
Not listed

Published

August 7, 2026

Last Modified

September 9, 2026

Advisory Details (2)

Auto-updated Aug 7, 2026
Patch available. Sources: github, github_commit.
github_commit

commit d6dc595f84b7 (jupyterhub/jupyterhub)

Fix landed in jupyterhub/jupyterhub commit d6dc595f84b7 — awaiting tagged release

https://github.com/jupyterhub/jupyterhub/commit/d6dc595f84b7509969686da31d87d6d69e7fce0a
github Patch Available

Unauthenticated Denial of Service via Unbounded Username Logging on Failed Login · Advisory · jupyterhub/jupyterhub · GitHub

https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-p43p-whwx-q52h

Vendor Advisories for CVE-2026-54338(1)

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

Affected Packages

(4 across 4 ecosystems)
Debian:12(1)
PackageVulnerable rangeFixed inDependents
jupyterhub3.0.0+ds1-1 ... 5.2.1+ds1-5 (10 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
jupyterhub5.2.1+ds1-4, 5.2.1+ds1-5——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
jupyterhub5.2.1+ds1-4, 5.2.1+ds1-5——
PyPI(1)
PackageVulnerable rangeFixed inDependents
jupyterhub0.1.0 ... 5.4.6 (96 versions)5.5.0—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 46× 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. 2026-09-19 04:38 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-18 04:14 UTCEG score recompute
  4. 2026-09-17 19:31 UTCEPSS rescore
  5. 2026-09-17 03:50 UTCEG score recompute
  6. 2026-09-16 14:08 UTCEPSS rescore
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-16 02:49 UTCEG score recompute
  9. 2026-09-14 00:51 UTCEG score recompute
  10. 2026-09-13 16:47 UTCEPSS rescore
  11. 2026-09-13 00:27 UTCEG score recompute
  12. 2026-09-12 00:03 UTCEG score recompute
  13. 2026-09-11 14:53 UTCEPSS rescore
  14. 2026-09-10 23:04 UTCEG score recompute
  15. 2026-09-10 09:35 UTCEPSS rescore
  16. 2026-09-09 05:59 UTCEG score recompute
  17. 2026-09-08 22:01 UTCEPSS rescore
  18. 2026-09-07 17:42 UTCEG score recompute
  19. 2026-09-07 16:01 UTCEPSS rescore
  20. 2026-09-06 13:47 UTCEPSS rescore
  21. 2026-09-06 09:38 UTCEG score recompute
  22. 2026-09-05 09:14 UTCEG score recompute
  23. 2026-09-04 08:50 UTCEG score recompute
  24. 2026-09-04 05:06 UTCEPSS rescore
  25. 2026-09-03 04:02 UTCEG score recompute
Show 48 more
  1. 2026-09-02 14:12 UTCEPSS rescore
  2. 2026-09-01 22:50 UTCEG score recompute
  3. 2026-09-01 13:54 UTCEPSS rescore
  4. 2026-09-01 04:40 UTCEPSS rescore
  5. 2026-08-31 22:26 UTCEG score recompute
  6. 2026-08-30 19:17 UTCEPSS rescore
  7. 2026-08-30 16:21 UTCEG score recompute
  8. 2026-08-30 01:22 UTCEPSS rescore
  9. 2026-08-29 15:57 UTCEG score recompute
  10. 2026-08-28 21:41 UTCEPSS rescore
  11. 2026-08-27 08:47 UTCEG score recompute
  12. 2026-08-26 14:46 UTCEPSS rescore
  13. 2026-08-26 08:22 UTCEG score recompute
  14. 2026-08-25 13:49 UTCEPSS rescore
  15. 2026-08-25 07:58 UTCEG score recompute
  16. 2026-08-23 07:10 UTCEG score recompute
  17. 2026-08-23 00:19 UTCEPSS rescore
  18. 2026-08-22 06:46 UTCEG score recompute
  19. 2026-08-21 23:49 UTCEPSS rescore
  20. 2026-08-21 06:22 UTCEG score recompute
  21. 2026-08-20 22:55 UTCEPSS rescore
  22. 2026-08-20 05:58 UTCEG score recompute
  23. 2026-08-19 17:04 UTCEPSS rescore
  24. 2026-08-19 05:33 UTCEG score recompute
  25. 2026-08-18 13:48 UTCEPSS rescore
  26. 2026-08-18 05:10 UTCEG score recompute
  27. 2026-08-17 13:47 UTCEPSS rescore
  28. 2026-08-17 04:45 UTCEG score recompute
  29. 2026-08-16 14:56 UTCEPSS rescore
  30. 2026-08-16 04:21 UTCEG score recompute
  31. 2026-08-16 02:14 UTCEPSS rescore
  32. 2026-08-15 03:58 UTCEG score recompute
  33. 2026-08-15 01:30 UTCEPSS rescore
  34. 2026-08-14 03:33 UTCEG score recompute
  35. 2026-08-13 22:00 UTCEPSS rescore
  36. 2026-08-13 03:10 UTCEG score recompute
  37. 2026-08-12 13:51 UTCEPSS rescore
  38. 2026-08-12 02:46 UTCEG score recompute
  39. 2026-08-11 02:22 UTCEG score recompute
  40. 2026-08-11 01:28 UTCEG score recompute
  41. 2026-08-11 00:00 UTCEPSS rescore
  42. 2026-08-09 22:19 UTCEG score recompute
  43. 2026-08-09 13:46 UTCEPSS rescore
  44. 2026-08-08 21:56 UTCEG score recompute
  45. 2026-08-08 16:37 UTCEPSS rescore
  46. 2026-08-07 21:32 UTCEG score recompute
  47. 2026-08-07 21:02 UTCEG score recompute
  48. 2026-08-07 21:02 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-54338?
CVE-2026-54338 is a medium vulnerability published on August 7, 2026. JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. Prior to 5.5.0, invalid input to form-based login authenticators can place an unbounded attacker-controlled username in failed-login logs, allowing an unauthenticated attacker to consume logging and…
When was CVE-2026-54338 disclosed?
CVE-2026-54338 was first published in the National Vulnerability Database on August 7, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-54338 actively exploited?
CVE-2026-54338 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 79.0% of all scored CVEs.
What is the CVSS score of CVE-2026-54338?
CVE-2026-54338 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-54338?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-54338, 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-2026-54338

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