CVE-2026-25904 Overly permissive Deno configuration in mcp-run-python leads to SSRF
Attackers can exploit overly permissive Deno sandbox settings in mcp-run-python to perform Server-Side Request Forgery against the host localhost.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-25904?
CVE-2026-25904 is a medium-severity server-side request forgery vulnerability in mcp-run-python, published on 9 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
The Pydantic-AI MCP Run Python tool configures the Deno sandbox with an overly permissive configuration that allows the underlying Python code to access the localhost interface of the host to perform SSRF attacks. Note - the "mcp-run-python" project is archived and unlikely to receive a fix.
Weakness: CWE-918
Which versions are affected by CVE-2026-25904?
3 open source packages ship an affected version, including mcp-run-python.
| Package | Affected | Fixed in |
|---|---|---|
mcp-run-python PyPI | All versions to 0.0.22 | None |
mcp-run-python PyPI | All versions to 0.0.22 | None |
mcp-run-python PyPI | All versions to 0.0.22 | None |
How do I fix CVE-2026-25904?
No fix has been published for CVE-2026-25904 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-25904 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-25904 exists.
Sources
Also known as GHSA-6fgp-m6q4-j3q5, PYSEC-2026-2627.