CVE-2026-59822NVD

Vulnerability Summary

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.

Severity Level

HIGH(8.8)

Published Date

Jul 8, 2026

Last Modified

Sep 3, 2026

Exploitation Status

ACTIVE

EPSS Score (30-Day)

0.84%Probability

Root Weakness (CWE)

N/A

CVSS v4.0 Base Metrics — Score 8.8

Attack VectorNetwork

Attack ComplexityLow

Attack RequirementsNone

Privileges RequiredNone

User InteractionNone

Confidentiality (Vulnerable System)High

Integrity (Vulnerable System)Low

Availability (Vulnerable System)None

Confidentiality (Subsequent System)None

Integrity (Subsequent System)None

Availability (Subsequent System)None

Affected & Patched Versions

Affected Versions

litellm < 1.84.0

Patched Versions

litellm >= 1.84.0

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