How severe is CVE-2025-61669?

No CVSS score has been assigned to CVE-2025-61669 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2025-61669?

CVE-2025-61669 affects the following packages: jupyter-server (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2025-61669?

Update jupyter-server to 2.18.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-61669 is resolved across your whole dependency graph.

How do I detect CVE-2025-61669 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jupyter-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2025-61669 if there is no patch (or I can't update yet)?

Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Is CVE-2025-61669 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-61669 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2025-61669?

CVE-2025-61669 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 16th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2025-61669?

CVE-2025-61669 is classified as Open Redirect (CWE-601). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2025-61669 published, and has it been updated?

CVE-2025-61669 was published on May 5, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

CVE-2025-61669 — jupyter-server

CVE-2025-61669 is a Open Redirect vulnerability in jupyter-server. A fix is available for jupyter-server — see the affected versions and patch details below.

jupyter_server next parameter open redirect can redirect users to external domains

Also known asGHSA-qh7q-6qm3-653wPYSEC-2026-67

Published

May 5, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-61669.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs16th percentile — riskier than 16% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐍jupyter-server

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Summary

The ?next=... URL query parameter has an open redirection vulnerability. In jupyter_server<=2.17.0, this URL query parameter allows redirection to arbitrary external domains, which can be exploited to facilitate phishing attacks on server users.

Details

The vulnerability is caused by insufficient validation in the LoginFormHandler._redirect_safe() method.

Source code reference: https://github.com/jupyter-server/jupyter_server/blob/987ebdd5e188cdc49751b01a0d6782d686492a53/jupyter_server/auth/login.py#L33-L76

This vulnerability was originally reported by Noriaki Iwasaki. All discovery credit goes to them.

PoC

Navigate to http://localhost:8888/login?next=///google.com
Observe that the user is redirected to google.com despite it being an external domain.

The external domain passed in the ?next parameter may be replaced with a malicious lookalike to facilitate phishing attacks. Jupyter Server deployments served on a public domain are especially vulnerable, as prod.company.com may be redirected to a look-alike URL such as prod.company.dev.

Impact

This vulnerability affects all users, especially enterprise users who work with sensitive/confidential data.

Patches

Jupyter Server 2.18+

Workaround

None.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`jupyter-server`	all versions	2.18.0`pip install --upgrade 'jupyter-server==2.18.0'`

Affected Products

1 product · 1 configurations

Application

jupyter serverjupyter

< 2.18.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jupyter-server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update jupyter-server to 2.18.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-61669 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Source: Red Hat security advisory for CVE-2025-61669 (CC BY 4.0)

Frequently Asked Questions

### Summary The `?next=...` URL query parameter has an open redirection vulnerability. In `jupyter_server<=2.17.0`, this URL query parameter allows redirection to arbitrary external domains, which can be exploited to facilitate phishing attacks on server users. ### Details The vulnerability is caused by insufficient validation in the `LoginFormHandler._redirect_safe()` method. - Source code reference: https://github.com/jupyter-server/jupyter_server/blob/987ebdd5e188cdc49751b01a0d6782d686492a53/jupyter_server/auth/login.py#L33-L76 This vulnerability was originally reported by Noriaki Iwas

O3 Security · Impact-Aware SCA

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