Is CVE-2025-61669 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2025-61669 being exploited in the wild.

How severe is CVE-2025-61669?

Medium severity, with a CVSS score of 6.1, published 5 May 2026.

Which products and versions are affected?

jupyter-server (PyPI) ECOSYSTEM:introduced=0,fixed=2.18.0.

Is there a fix for CVE-2025-61669?

Yes. jupyter-server (PyPI): upgrade to 2.18.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2025-61669 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2025-61669?

Check whether you run Jupyter Server or jupyter-server (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2025-61669: Jupyter Server open redirect in LoginFormHandler via next parameter

CVE-2025-61669 · Severity: medium · CVSS 6.1 · Published 2026-05-05

Jupyter Server, the backend for Jupyter web applications, contains a vulnerability that allows attackers to redirect users to malicious websites. By tricking a user into clicking a specially crafted link, an attacker can send them to a fake login page or a site hosting malware while making it appear as though the user is still on their trusted Jupyter domain. This is primarily used to steal login credentials or sensitive data through phishing.

Technologies: Jupyter Server, jupyter-server (PyPI). Vendors: Jupyter, PyPI.

Quick answers

Is CVE-2025-61669 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2025-61669 being exploited in the wild.
How severe is CVE-2025-61669?: Medium severity, with a CVSS score of 6.1, published 5 May 2026.
Which products and versions are affected?: jupyter-server (PyPI) ECOSYSTEM:introduced=0,fixed=2.18.0.
Is there a fix for CVE-2025-61669?: Yes. jupyter-server (PyPI): upgrade to 2.18.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2025-61669 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2025-61669?: Check whether you run Jupyter Server or jupyter-server (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

jupyter-server (PyPI): upgrade to 2.18.0 or later
```
pip install "jupyter-server>=2.18.0"
```

Technical details

An open redirect vulnerability (CWE-601) exists in Jupyter Server due to insufficient validation in the 'LoginFormHandler._redirect_safe()' method. The 'next' URL query parameter fails to properly sanitize input, allowing an attacker to use a triple-slash prefix (e.g., '///google.com') to bypass internal redirection checks and force a redirect to an external domain. This can be exploited by sending a crafted URL to a user; if the user interacts with the link, they are redirected to an arbitrary site. The issue is fixed in Jupyter Server version 2.18.0.

Affected products

Jupyter Project jupyter-server <= 2.17.0

Identifiers

CVE-2025-61669
GHSA-qh7q-6qm3-653w
PYSEC-2026-67

Timeline

2026-05-05: disclosed
2026-05-05: advisory
2026-05-05: patched

References

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