High 7.6Published May 5, 2026

CVE-2026-40934jupyter-server authentication cookies remain valid after password reset due to static cookie secret

Updated under an hour ago (Oct 26, 2026, 5:23 AM ET)

Does this affect you?

It affects jupyter-server jupyter_server and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for jupyter-server jupyter_server

Exploited in the last 30 days

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.

CVSS: 7.6 HIGH (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Weakness (CWE): CWE-613
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: May 7, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

jupyter-server jupyter_server jupyter_server:jupyter_server (from the name)	before 2.18.0	CNA record
jupyter jupyter_server jupyter:jupyter_server	before 2.18.0	NVD

References

https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5mrq-x3x5-8v8fx-refsource-confirm, exploit, mitigation, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.