Vulnerability Report

CVE-2026-59822

CISA KEV Active

Title: LiteLLM Unauthenticated Authorization Bypass

Auth Bypass

Proof Of Concept

PoC Available for CVE-2026-59822

CWE Category CWE-287

Published Date Jul 08, 2026

Modified Date Sep 03, 2026

Exploit Status Available

Score 8.8 CVSS v4.0

Exploit Probability (EPSS)

0.84%

Vulnerability Summary

CVE-2026-59822: 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.

Impacted Vendors

litellm 1

Reference Links

https://github.com/BerriAI/litellm/commit/73869f0faf7d11ee21adcb5f91b8c33a340b6c2c https://github.com/BerriAI/litellm/pull/26463 https://github.com/BerriAI/litellm/releases/tag/v1.84.0 https://github.com/BerriAI/litellm/security/advisories/GHSA-7488-6r32-c95q

CVSS v4.0

Source Entity [email protected]

Severity HIGH

8.8

Attack Vector

NETWORK

Complexity

LOW

Privileges

N/A

Interaction

NONE

Confidentiality

N/A

Integrity

N/A

Availability

N/A

Scope

N/A

RAW VECTOR

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1