CVE-2025-61669

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.

Score

CVSS 4.0 6.3 Medium

Status

Analyzed - security-advisories@github.com

Published

2026-05-05

Last modified

2026-10-07

Weaknesses

CWE-601

Affected products

• Jupyter Server (Jupyter)
• Jupyter Server (Jupyter-server)

References

• https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-qh7q-6qm3-653w