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CVE-2026-59822

LiteLLM: MCP Authentication Bypass via OAuth2 Passthrough Fallback PUBLISHED

Description (CNA)

LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.84.0, LiteLLM's MCP Streamable HTTP endpoint allowed an unauthenticated attacker to use a fabricated Authorization header to trigger an OAuth2 passthrough fallback path that replaced failed LiteLLM key validation with an empty UserAPIKeyAuth() object, allowing requests to reach MCP tooling without a valid LiteLLM key. This issue is fixed in version 1.84.0.

Affected (CNA)

Vendor / productVersions
BerriAI / litellmaffected < 1.84.0

CWE

CWE-287, CWE-306

References

ADP enrichment

CISA-ADP

No English description supplied.