CVE-2026-40934

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 v3 6.8 MEDIUM

6.8^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.6 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5mrq-x3x5-8v8f	Exploit Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:jupyter:jupyter_server:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-05-05 22:16

Updated : 2026-07-25 11:10

NVD link : CVE-2026-40934

Mitre link : CVE-2026-40934

CVE.ORG link : CVE-2026-40934

JSON object : View

Products Affected

jupyter

jupyter_server

CWE

CWE-613

Insufficient Session Expiration

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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."}, {"lang": "es", "value": "Jupyter Server es el backend para las aplicaciones web de Jupyter. En las versiones 2.17.0 y anteriores, el secreto utilizado para firmar las cookies de autenticaci\u00f3n se persiste en un archivo est\u00e1tico en ~/.local/share/jupyter/runtime/jupyter_cookie_secret y nunca se rota cuando un usuario cambia su contrase\u00f1a. Despu\u00e9s de un restablecimiento de contrase\u00f1a y un reinicio del servidor, cualquier cookie de autenticaci\u00f3n emitida previamente permanece criptogr\u00e1ficamente v\u00e1lida porque la clave de firma no ha cambiado. Un atacante que ha capturado una cookie de sesi\u00f3n por cualquier medio retiene acceso autenticado completo al servidor independientemente de los cambios de contrase\u00f1a posteriores. Esto afecta a las implementaciones que utilizan autenticaci\u00f3n basada en contrase\u00f1a, particularmente servidores compartidos o de cara al p\u00fablico donde se espera que la rotaci\u00f3n de credenciales revoque las sesiones existentes. Este problema ha sido solucionado en la versi\u00f3n 2.18.0."}], "lastModified": "2026-07-25T11:10:00.100", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:jupyter:jupyter_server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "E0B6C703-7E28-4F23-9878-E157975C32A4", "versionEndExcluding": "2.18.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}