CVE-2026-12773: LiteLLM

Critical severity, CVSS 9.8. EPSS: 1% chance of exploitation in the next 30 days.

A weakness has been identified in BerriAI litellm up to 1.59.8. Affected is the function UserAPIKeyAuth of the file litellm/proxy/_experimental/mcp_server/auth/user_api_key_auth_mcp.py of the component MCP Proxy. Executing a manipulation can lead to improper authentication. The attack may be launched remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure.

Affected products

• LiteLLM LiteLLM: before 1.59.9 (fixed in 1.59.9)

Published 2026-06-21. Last modified 2026-07-15.