CVE-2026-54338

MEDIUMPre-NVD 5.35.3
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (36th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
5.3EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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
5.3MEDIUMmedium confidence
EG Risk
39
EG Risk 39/100

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 (value × EchelonGraph’s weight)
Severity53% × 45%
The EG Score, 5.3 of 10.
Exploitation0.4% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.4%
EPSS %ILE
36th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

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 advisoryMentions a patch (unverified)

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 rangeFix by version rangeDependents
jupyterhub3.0.0+ds1-1 ... 5.2.1+ds1-5 (10 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
jupyterhub5.2.1+ds1-4, 5.2.1+ds1-5
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
jupyterhub5.2.1+ds1-4, 5.2.1+ds1-5
  • every version on: no fix on record
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
jupyterhub0.1.0 ... 5.4.6 (96 versions)
  • every version up to 5.5.0: fixed in 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 / 45× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 110 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 10 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  3. 2026-10-12 15:56 UTCEG score recompute
  4. 2026-10-11 19:39 UTCEG score recompute
  5. 2026-10-11 16:54 UTCEG score recompute
  6. 2026-10-11 14:18 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  10. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  11. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  12. 2026-10-06 23:16 UTCEG score recompute
  13. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  14. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  15. 2026-10-05 08:11 UTCEG score recompute
  16. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  17. 2026-10-04 05:42 UTCEG score recompute
  18. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  19. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  20. 2026-10-02 09:29 UTCEG score recompute
  21. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  22. 2026-09-30 22:54 UTCEG score recompute
  23. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  24. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  25. 2026-09-29 05:42 UTCEG score recompute
Show 75 more
  1. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  2. 2026-09-27 17:07 UTCEG score recompute
  3. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  4. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  5. 2026-09-25 04:13 UTCEG score recompute
  6. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.4% · 35th percentile
  7. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  8. 2026-09-23 13:46 UTCEG score recompute
  9. 2026-09-22 12:01 UTCEG score recompute
  10. 2026-09-21 11:34 UTCEG score recompute
  11. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  12. 2026-09-20 05:07 UTCEG score recompute
  13. 2026-09-19 04:38 UTCEG score recompute
  14. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  15. 2026-09-18 04:14 UTCEG score recompute
  16. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  17. 2026-09-17 03:50 UTCEG score recompute
  18. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  19. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  20. 2026-09-16 02:49 UTCEG score recompute
  21. 2026-09-14 00:51 UTCEG score recompute
  22. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  23. 2026-09-13 00:27 UTCEG score recompute
  24. 2026-09-12 00:03 UTCEG score recompute
  25. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  26. 2026-09-10 23:04 UTCEG score recompute
  27. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  28. 2026-09-09 05:59 UTCEG score recompute
  29. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  30. 2026-09-07 17:42 UTCEG score recompute
  31. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  32. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  33. 2026-09-06 09:38 UTCEG score recompute
  34. 2026-09-05 09:14 UTCEG score recompute
  35. 2026-09-04 08:50 UTCEG score recompute
  36. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  37. 2026-09-03 04:02 UTCEG score recompute
  38. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  39. 2026-09-01 22:50 UTCEG score recompute
  40. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  41. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  42. 2026-08-31 22:26 UTCEG score recompute
  43. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  44. 2026-08-30 16:21 UTCEG score recompute
  45. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  46. 2026-08-29 15:57 UTCEG score recompute
  47. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  48. 2026-08-27 08:47 UTCEG score recompute
  49. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  50. 2026-08-26 08:22 UTCEG score recompute
  51. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  52. 2026-08-25 07:58 UTCEG score recompute
  53. 2026-08-23 07:10 UTCEG score recompute
  54. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  55. 2026-08-22 06:46 UTCEG score recompute
  56. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  57. 2026-08-21 06:22 UTCEG score recompute
  58. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  59. 2026-08-20 05:58 UTCEG score recompute
  60. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  61. 2026-08-19 05:33 UTCEG score recompute
  62. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  63. 2026-08-18 05:10 UTCEG score recompute
  64. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  65. 2026-08-17 04:45 UTCEG score recompute
  66. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  67. 2026-08-16 04:21 UTCEG score recompute
  68. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  69. 2026-08-15 03:58 UTCEG score recompute
  70. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  71. 2026-08-14 03:33 UTCEG score recompute
  72. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  73. 2026-08-13 03:10 UTCEG score recompute
  74. 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  75. 2026-08-12 02:46 UTCEG score recompute

Related CVEs(same product + same CWE)

Frequently asked(5)

What is CVE-2026-54338?
CVE-2026-54338 is a medium-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-54338 published?
The CVE record for CVE-2026-54338 was published on August 7, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 9, 2026; the record at its source may have been updated since.
Is CVE-2026-54338 actively exploited?
CVE-2026-54338 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (36th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-54338?
CVE-2026-54338 has a CVSS base score of 5.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-54338?
A fix for CVE-2026-54338 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-54338 are linked in the Vendor Advisories panel on this page.

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