5.4

CVE-2026-40864: jupyter jupyterhub Cross-Site Request Forgery (CSRF)

CVSS: 5.4v3.1MediumAnalyzed
AliasesGHSA-m68r-v472-jgq9BIT-jupyterhub-2026-40864PYSEC-2026-2189
Published 22-05-2026Last modified 26-05-2026
Open JSON

Vulnerability summary

CVE-2026-40864 is a medium (CVSS 5.4) Cross-Site Request Forgery (CSRF) vulnerability in jupyter jupyterhub. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7% of scored vulnerabilities.

Overall risk
22/100
0100
Low · default modelHow is this calculated?
CVSS score
5.4/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.18%
0%100%
Low · +0.02 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 0 · Related 1
CGA-J4F5-X3C7-639G

Timeline

  1. 22-05-2026
    PublishedVulnerability first disclosed.
  2. 26-05-2026
    Last modifiedVulnerability information updated.

Description

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 metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.18%

Chance of exploitation in the next 30 days

Percentile

7%

Versus all other CVEs

30-day change

+0.02 pp

From 0.16% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.18%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard4 products
  • py3.10-jupyterhub< 5.4.6-r0
  • py3.11-jupyterhub< 5.4.5-r0 | < 5.4.6-r0
  • py3.12-jupyterhub< 5.4.6-r0
  • py3.13-jupyterhub< 5.4.6-r0
Wolfi4 products
  • py3.10-jupyterhub< 5.4.6-r0
  • py3.11-jupyterhub< 5.4.5-r0 | < 5.4.6-r0
  • py3.12-jupyterhub< 5.4.6-r0
  • py3.13-jupyterhub< 5.4.6-r0
Debian1 product
  • jupyterhubAll versions (No fix recorded)
Jupyter1 product
Jupyterhub1 product
PyPI1 product
  • jupyterhub≥ 4.1.0, < 5.4.5
Ubuntu1 product
  • jupyterhubAll versions (No fix recorded)

7 vendors · 13 products

References

8 links