Home

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.

PUBLISHED Reserved 2026-04-15 | Published 2026-05-05 | Updated 2026-05-07 | Assigner GitHub_M




HIGH: 7.6CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Problem types

CWE-613: Insufficient Session Expiration

Product status

< 2.18.0
affected

References

github.com/...server/security/advisories/GHSA-5mrq-x3x5-8v8f

cve.org (CVE-2026-40934)

nvd.nist.gov (CVE-2026-40934)

Download JSON