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Severe, 6 weeks1496Projects326

1496 severe, 6 weeks · 326 projects

LiteLLMGHSA-v4p8-mg3p-g94g

LiteLLM: Authenticated command execution via MCP stdio test endpoints

LiteLLM

CVE-2026-42271 · Published Apr 25, 2026 · updated Sep 10, 2026

High8.8
Fix: upgrade to 1.83.7 or later
GitHub advisory

Impact

Two endpoints used to preview an MCP server before saving it , POST /mcp-rest/test/connection and POST /mcp-rest/test/tools/list , accepted a full server configuration in the request body, including the command, args, and env fields used by the stdio transport. When called with a stdio configuration, the endpoints attempted to connect, which spawned the supplied command as a subprocess on the proxy host with the privileges of the proxy process.

The endpoints were gated only by a valid proxy API key, with no role check. Any authenticated user , including holders of low-privilege internal-user keys , could therefore run arbitrary commands on the host.

Patches

Fixed in **1.83.7**. Both test endpoints now require the PROXY_ADMIN role, bringing them into line with the save endpoint.

Workarounds

If upgrading is not immediately possible, developers should block POST /mcp-rest/test/connection and POST /mcp-rest/test/tools/list at their reverse proxy or API gateway.

Affected versions

PackageAffectedFixed in
litellm
PyPI
>= 1.74.2, < 1.83.71.83.7
Details and references

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