CVE-2026-35030

Affected versions of the litellm package are vulnerable to Authentication Bypass due to the use of an insufficiently unique cache key derived from only the first 20 characters of a JWT token in the OIDC userinfo cache. When JWT authentication is enabled, the cache key is computed as token[:20], and because JWT headers produced by the same signing algorithm generate identical prefixes, an attacker can craft a token whose first 20 characters collide with a legitimate cached entry. This allows an unauthenticated attacker to inherit the identity and permissions of a legitimate user on cache hit, resulting in full authentication bypass on deployments with JWT/OIDC authentication enabled.