What is CVE-2025-61669?

CVE-2025-61669 is a medium-severity vulnerability in Jupyter Server, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2026-05-05.

How severe is CVE-2025-61669?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Open Redirect in Jupyter Server

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.

Vulnerability class: Open Redirect

EPSS: 0.003 (18.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

Jupyter Jupyter_server
Jupyter-server Jupyter_server — versions <= 2.17.0

Weakness classification (CWE)

CWE-601 — URL Redirection to Untrusted Site (Open Redirect)

References

security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)

Frequently asked questions

What is CVE-2025-61669?: CVE-2025-61669 is a medium-severity vulnerability in Jupyter Server, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2026-05-05.
How severe is CVE-2025-61669?: Medium severity. CVSS v3 base score is 6.1 out of 10.