BerriAI litellm <=1.59.8 MCP Proxy auth flaw (UserAPIKeyAuth)
CVE-2026-12773 Published on June 21, 2026
BerriAI litellm MCP Proxy user_api_key_auth_mcp.py UserAPIKeyAuth improper authentication
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.
Timeline
Advisory disclosed
VulDB entry created
VulDB entry last update
Weakness Type
What is an authentification Vulnerability?
When an actor claims to have a given identity, the software does not prove or insufficiently proves that the claim is correct.
CVE-2026-12773 has been classified to as an authentification vulnerability or weakness.
Products Associated with CVE-2026-12773
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Affected Versions
BerriAI litellm:- Version 1.59.0 is affected.
- Version 1.59.1 is affected.
- Version 1.59.2 is affected.
- Version 1.59.3 is affected.
- Version 1.59.4 is affected.
- Version 1.59.5 is affected.
- Version 1.59.6 is affected.
- Version 1.59.7 is affected.
- Version 1.59.8 is affected.