CVE-2026-42271 — HIGH (CVSS 8.8) AI Security Vulnerability

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. From version 1.74.2 to before version 1.83.7, 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...

Full CISO analysis pending enrichment.

Affected Systems

Package	Ecosystem	Vulnerable Range	Patched
litellm	pip	—	No patch
45.5K OpenSSF 6.2 4 dependents Pushed 5d ago 53% patched ~43d to patch Full package profile →

Do you use litellm? You're affected.

Severity & Risk

CVSS 3.1

8.8 / 10

EPSS

N/A

Exploitation Status

No known exploitation

Sophistication

N/A

Attack Surface

AV Network

AC Low

PR Low

UI None

S Unchanged

C High

I High

A High

Recommended Action

No patch available

Monitor for updates. Consider compensating controls or temporary mitigations.

Compliance Impact

Compliance analysis pending. Sign in for full compliance mapping when available.

Frequently Asked Questions

What is CVE-2026-42271?

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. From version 1.74.2 to before version 1.83.7, 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 com

Is CVE-2026-42271 actively exploited?

No confirmed active exploitation of CVE-2026-42271 has been reported, but organizations should still patch proactively.

How to fix CVE-2026-42271?

No patch is currently available. Monitor vendor advisories for updates.

What is the CVSS score for CVE-2026-42271?

CVE-2026-42271 has a CVSS v3.1 base score of 8.8 (HIGH).

Technical Details

NVD Description

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. From version 1.74.2 to before version 1.83.7, 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. This issue has been patched in version 1.83.7.