Vulnerability Report

CVE-2026-35030

Title: Authentication Bypass in LiteLLM due to JWT cache key collision

Auth Bypass

Proof Of Concept

PoC Available for CVE-2026-35030

CWE Category CWE-287

Published Date Apr 06, 2026

Modified Date Apr 07, 2026

Exploit Status Available

Score 9.4 CVSS v4.0

Exploit Probability (EPSS)

0.39%

Vulnerability Summary

CVE-2026-35030: LiteLLM is a proxy server (AI Gateway) to call LLM APIs in OpenAI (or native) format. Prior to 1.83.0, when JWT authentication is enabled (enable_jwt_auth: true), the OIDC userinfo cache uses token[:20] as the cache key. JWT headers produced by the same signing algorithm generate identical first 20 characters. This configuration option is not enabled by default. Most instances are not affected. An unauthenticated attacker can craft a token whose first 20 characters match a legitimate user's cached token. On cache hit, the attacker inherits the legitimate user's identity and permissions. This affects deployments with JWT/OIDC authentication enabled. Fixed in v1.83.0.

Impacted Vendors

litellm 1

Reference Links

https://github.com/BerriAI/litellm/security/advisories/GHSA-jjhc-v7c2-5hh6

CVSS v4.0

Source Entity [email protected]

Severity CRITICAL

9.4

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:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/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

Source Entity 134c704f-9b21-4f2e-91b3-4a467353bcc0