LiteLLM: Authentication bypass via OIDC userinfo cache key collision
LiteLLM: Authentication bypass via OIDC userinfo cache key collision
Critical severity. Affects litellm < 1.83.0. Upgrade to 1.83.0 or later.
CVE-2026-35030 / GHSA-jjhc-v7c2-5hh6 · severity: critical · PyPI
Affected
litellm< 1.83.0 → fixed in 1.83.0
Details
Impact
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.
Patches
Fixed in v1.83.0. The cache key now uses the full hash of the JWT token.
Workarounds
Disable OIDC userinfo caching by setting the cache TTL to 0, or disable JWT authentication entirely.
Source: GHSA-jjhc-v7c2-5hh6 — GitHub Advisory Database (CC-BY-4.0).