Is CVE-2026-40934 actively exploited?

No active exploitation of CVE-2026-40934 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-40934 be exploited remotely?

Yes. CVE-2026-40934 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-40934?

CVE-2026-40934 has a CVSS score of 6.8 (MEDIUM).

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MEDIUM

CVE-2026-40934

CWE-613Published: May 5, 2026· Updated: May 11, 2026

6.8

CVSS v3.1

EPSS:0.07%probability of exploitation in 30 daysPercentile:20.0th

Official 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.

NVD Source

Technical Analysis

CVE-2026-40934 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), with a CVSS base score of 6.8.