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 80% 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
20%
KEV
Not listed

Published

August 7, 2026

Last Modified

August 11, 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

(3 across 3 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——

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 41× 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. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-29 15:57 UTCEG score recompute
  3. 2026-08-28 21:41 UTCEPSS rescore
  4. 2026-08-27 08:47 UTCEG score recompute
  5. 2026-08-26 14:46 UTCEPSS rescore
  6. 2026-08-26 08:22 UTCEG score recompute
  7. 2026-08-25 13:49 UTCEPSS rescore
  8. 2026-08-25 07:58 UTCEG score recompute
  9. 2026-08-23 07:10 UTCEG score recompute
  10. 2026-08-23 00:19 UTCEPSS rescore
  11. 2026-08-22 06:46 UTCEG score recompute
  12. 2026-08-21 23:49 UTCEPSS rescore
  13. 2026-08-21 06:22 UTCEG score recompute
  14. 2026-08-20 22:55 UTCEPSS rescore
  15. 2026-08-20 05:58 UTCEG score recompute
  16. 2026-08-19 17:04 UTCEPSS rescore
  17. 2026-08-19 05:33 UTCEG score recompute
  18. 2026-08-18 13:48 UTCEPSS rescore
  19. 2026-08-18 05:10 UTCEG score recompute
  20. 2026-08-17 13:47 UTCEPSS rescore
  21. 2026-08-17 04:45 UTCEG score recompute
  22. 2026-08-16 14:56 UTCEPSS rescore
  23. 2026-08-16 04:21 UTCEG score recompute
  24. 2026-08-16 02:14 UTCEPSS rescore
  25. 2026-08-15 03:58 UTCEG score recompute
Show 16 more
  1. 2026-08-15 01:30 UTCEPSS rescore
  2. 2026-08-14 03:33 UTCEG score recompute
  3. 2026-08-13 22:00 UTCEPSS rescore
  4. 2026-08-13 03:10 UTCEG score recompute
  5. 2026-08-12 13:51 UTCEPSS rescore
  6. 2026-08-12 02:46 UTCEG score recompute
  7. 2026-08-11 02:22 UTCEG score recompute
  8. 2026-08-11 01:28 UTCEG score recompute
  9. 2026-08-11 00:00 UTCEPSS rescore
  10. 2026-08-09 22:19 UTCEG score recompute
  11. 2026-08-09 13:46 UTCEPSS rescore
  12. 2026-08-08 21:56 UTCEG score recompute
  13. 2026-08-08 16:37 UTCEPSS rescore
  14. 2026-08-07 21:32 UTCEG score recompute
  15. 2026-08-07 21:02 UTCEG score recompute
  16. 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 August 11, 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 79.7% 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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