LiteLLM: Authenticated command execution via MCP stdio test endpoints
CISA confirms exploitation of this vulnerability in real attacks. Prioritise checking whether your application is affected. CISA KEV · CC0 1.0
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 software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | litellm | >= 1.74.2, < 1.83.7 | 1.83.7 |
References
- https://github.com/BerriAI/litellm/security/advisories/GHSA-v4p8-mg3p-g94g
- https://nvd.nist.gov/vuln/detail/CVE-2026-42271
- https://github.com/BerriAI/litellm
- https://github.com/BerriAI/litellm/releases/tag/v1.83.7-stable
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-42271
- https://pypi.org/project/litellm
- https://github.com/advisories/GHSA-v4p8-mg3p-g94g
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-77, CWE-78- Platform
- Python (PyPI)
- Package
litellm- Disclosed
- 25.04.2026
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-2599 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-v4p8-mg3p-g94g - CC BY 4.0
Vulnerability history: litellm
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 42
- First → latest
- 04.2024 09.2026
- Without a fix
- 14
- Exploited in attacks
- 3
Severity breakdown
- Critical 7
- High 17
- Medium 8
- Low 9
- Unrated 1
Disclosures per year
- 2024: 8
- 2025: 6
- 2026: 28
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LiteLLM: Authenticated command execution via MCP stdio test endpoints this entry
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