GHSA-4xpc-pv4p-pm3w: LiteLLM: Authentication Bypass via Host Header Injection

Summary

A Host-header parsing flaw in the LiteLLM proxy could let unauthenticated callers reach protected management routes. The auth layer derived the route from request.url.path, which Starlette rebuilds from the Host header, so a crafted Host made the gate check a different route than the one FastAPI dispatched. Most deployments are not affected, since upstream CDNs, WAFs, reverse proxies or load balancers that validate Host block the bypass, and LiteLLM Cloud customers are not affected.

Mitigation

Fixed in 1.84.0. Upgrade to 1.84.0 or later; no configuration change is required. If upgrading is not immediately possible, place the proxy behind an upstream component that validates or normalizes the Host header (a CDN/WAF, a reverse proxy with explicit server_name allowlists, or a cloud load balancer with host-based routing rules), or otherwise restrict network access to the proxy listener.

Affected packages in the Exposure Registry

Matched by package name and ecosystem. Each entry shows whether the package delegates to a language model and how many tracked packages depend on it.

• litellmPyPILLM dependency since 2023-07-27 · 55 tracked dependents

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