jupyter-server jupyter_server up to 2.17.0 Login LoginFormHandler._redirect_safe next

Summaryinfo

A vulnerability identified as problematic has been detected in jupyter-server jupyter_server up to 2.17.0. Affected is the function LoginFormHandler._redirect_safe of the component Login Handler. This manipulation of the argument Next causes redirect. This vulnerability is registered as CVE-2025-61669. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in jupyter-server jupyter_server up to 2.17.0. It has been declared as problematic. Affected by this vulnerability is the function LoginFormHandler._redirect_safe of the component Login Handler. The manipulation of the argument next with an unknown input leads to a redirect vulnerability. The CWE definition for the vulnerability is CWE-601. A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks. As an impact it is known to affect integrity. The summary by CVE is:

Jupyter Server is the backend for Jupyter web applications. In jupyter_server versions through 2.17.0, the next query parameter in the login flow is insufficiently validated in `LoginFormHandler._redirect_safe()`, which allows redirects to arbitrary external domains via values such as `///example.com`. An attacker can use a crafted login URL to redirect users to a malicious site and facilitate phishing attacks. This issue is fixed in version 2.18.0.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2025-61669 since 09/29/2025. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1204.001 according to MITRE ATT&CK.

Upgrading to version 2.18.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-209644). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• jupyter-server

Name

• jupyter_server

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13
• 2.14
• 2.15
• 2.16
• 2.17.0

Website

• Product: https://github.com/jupyter-server/jupyter_server/

CPE 2.3info

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CPE 2.2info

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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