CVE-2026-40864

MEDIUMNVD 5.45.4—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.4 under NVD CVSS v3. 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, nvd
Trending — 3 sources updated this week
5.4
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.4Exploit: NoneExposed: 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. In versions 4.1.0 through 5.4.4, XSRF protection (updated in 4.1.0) inappropriately treated requests with Sec-Fetch-Mode: no-cors as same-origin requests, bypassing XSRF checks. The JSON API is not affected, only HTTP form endpoints, such as /hub/spawn and /hub/accept-share, meaning attackers could trigger server spawn (but not access the server) and if the attacker is a JupyterHub user permitted to share access to their server, cause a user to accept a share and have access to the attacker's server. This issue has been fixed in version 5.4.5. If developers are unable to immediately upgrade, they can temporarily mitigate this issue by dropping requests to JupyterHub with Sec-Fetch-Mode: no-cors if they are using a reverse proxy.

CVSS v3
5.4
EG Score
5.4(medium)
EG Risk
24(Track)
EG Risk 24/100SSVC: 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
Severity54% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
5.5%
KEV
Not listed

Published

May 22, 2026

Last Modified

June 1, 2026

Advisory Details (2)

Auto-updated Jun 14, 2026
Patch available. Sources: github_commit, github.
github Patch Available

cross-origin form POSTs bypass XSRF · Advisory · jupyterhub/jupyterhub · GitHub

https://github.com/jupyterhub/jupyterhub/security/advisories/GHSA-m68r-v472-jgq9
github_commit

commit 9c5ec277d3cd (jupyterhub/jupyterhub)

Fix landed in jupyterhub/jupyterhub commit 9c5ec277d3cd — awaiting tagged release

https://github.com/jupyterhub/jupyterhub/commit/9c5ec277d3cda5a59de2d8c8117efa77bd941127

Vendor Advisories for CVE-2026-40864(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
jupyterhub4.1.0 ... 5.4.4 (20 versions)5.4.5—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 35× 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. 2026-07-23 03:11 UTCEG score recompute
  2. 2026-07-22 14:08 UTCEPSS rescore
  3. 2026-07-21 15:24 UTCEPSS rescore
  4. 2026-07-20 17:08 UTCEPSS rescore
  5. 2026-07-19 14:31 UTCEPSS rescore
  6. 2026-07-19 02:29 UTCEPSS rescore
  7. 2026-07-18 10:04 UTCEPSS rescore
  8. 2026-07-17 04:24 UTCOSV refresh
  9. 2026-07-16 17:03 UTCEPSS rescore
  10. 2026-07-15 16:57 UTCEPSS rescore
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  1. 2026-07-01 15:06 UTCEPSS rescore
  2. 2026-06-30 23:22 UTCEPSS rescore
  3. 2026-06-29 14:06 UTCEPSS rescore
  4. 2026-06-28 14:07 UTCEPSS rescore
  5. 2026-06-28 04:56 UTCEPSS rescore
  6. 2026-06-27 03:08 UTCEPSS rescore
  7. 2026-06-25 13:49 UTCEPSS rescore
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  9. 2026-06-24 14:05 UTCEPSS rescore
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  15. 2026-06-21 01:59 UTCEPSS rescore
  16. 2026-06-19 19:25 UTCEPSS rescore
  17. 2026-06-18 17:52 UTCEPSS rescore
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  19. 2026-06-17 17:53 UTCEPSS rescore
  20. 2026-06-16 17:52 UTCEPSS rescore
  21. 2026-06-15 17:49 UTCEPSS rescore
  22. 2026-06-13 23:00 UTCEPSS rescore
  23. 2026-06-12 23:12 UTCEPSS rescore
  24. 2026-06-12 23:12 UTCEPSS rescore
  25. 2026-06-11 14:00 UTCEPSS rescore
  26. 2026-06-10 13:22 UTCEPSS rescore
  27. 2026-06-10 13:22 UTCEPSS rescore
  28. 2026-06-08 14:17 UTCEPSS rescore
  29. 2026-06-08 14:17 UTCEPSS rescore
  30. 2026-06-07 15:25 UTCEPSS rescore
  31. 2026-06-07 15:25 UTCEPSS rescore
  32. 2026-06-05 22:47 UTCEPSS rescore
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  35. 2026-06-04 13:12 UTCEPSS rescore
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  37. 2026-06-02 20:13 UTCEPSS rescore
  38. 2026-06-01 13:52 UTCEPSS rescore
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  40. 2026-06-01 13:51 UTCEPSS rescore
  41. 2026-05-31 22:30 UTCEPSS rescore
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  43. 2026-05-31 00:16 UTCEPSS rescore
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  46. 2026-05-29 13:44 UTCEPSS rescore
  47. 2026-05-29 13:44 UTCEPSS rescore
  48. 2026-05-28 13:44 UTCEPSS rescore
  49. 2026-05-28 13:44 UTCEPSS rescore
  50. 2026-05-28 13:44 UTCEPSS rescore
  51. 2026-05-27 13:40 UTCEPSS rescore
  52. 2026-05-27 13:40 UTCEPSS rescore
  53. 2026-05-27 13:40 UTCEPSS rescore
  54. 2026-05-26 13:44 UTCEPSS rescore
  55. 2026-05-26 13:38 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-40864?
CVE-2026-40864 is a medium vulnerability published on May 22, 2026. JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. In versions 4.1.0 through 5.4.4, XSRF protection (updated in 4.1.0) inappropriately treated requests with Sec-Fetch-Mode: no-cors as same-origin requests, bypassing XSRF checks. The JSON API is not…
When was CVE-2026-40864 disclosed?
CVE-2026-40864 was first published in the National Vulnerability Database on May 22, 2026, with the most recent update on June 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40864 actively exploited?
CVE-2026-40864 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 5.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-40864?
CVE-2026-40864 has a CVSS v3 base score of 5.4 (NVD).
How do I remediate CVE-2026-40864?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40864, 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-2026-40864

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