CVE-2025-61669

Description

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.

CVSS v3.1 Score

6.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.01%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-601 CWE-601

Affected Products

Vendor	Product	Versions
jupyter	jupyter_server	< 2.18.0

References

Advisories & Patches

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

Exploits

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

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2025-61669? +

CVE-2025-61669 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2025-61669? +

CVE-2025-61669 affects products from jupyter, specifically: jupyter_server. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-61669? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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