Go to homepageCyberStrike

Menu

Star on GitHub · 3.2k
Sign inDownload

CVE-2026-40934

6.8 · MEDIUM

Jupyter Server is the backend for Jupyter web applications.

Published May 5, 2026CWE-613EPSS 0.38%

Overview

CVE-2026-40934 is a medium-severity vulnerability. It was published on May 5, 2026 and has a CVSS 3.1 base score of 6.8 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 6.8, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical description

Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the secret used to sign authentication cookies is persisted to a static file at ~/.local/share/jupyter/runtime/jupyter_cookie_secret and is never rotated when a user changes their password. After a password reset and server restart, any previously issued authentication cookie remains cryptographically valid because the signing key has not changed. An attacker who has captured a session cookie through any means retains full authenticated access to the server regardless of subsequent password changes. This affects deployments using password-based authentication, particularly shared or public-facing servers where credential rotation is expected to revoke existing sessions. This issue has been fixed in version 2.18.0.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/jupyter-server/jupyter_server/security/advisories/GHSA-5mrq-x3x5-8v8f

How CyberStrike helps

Frequently asked questions

What is CVE-2026-40934?

CVE-2026-40934 is a medium-severity vulnerability. It was published on May 5, 2026 and has a CVSS 3.1 base score of 6.8 (MEDIUM).

How severe is CVE-2026-40934?

This vulnerability has a CVSS 3.1 base score of 6.8, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-40934?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-40934?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-40934 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

Related MEDIUM CVEs from 2026

View all
Browse by year2026202520242023202220212020201920182017201620152014201320122011201020092008200720062005200420032002200120001999