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

• PyPI litellm: < 1.84.0 → fixed in 1.84.0

Impact A Host-header parsing flaw in the LiteLLM proxy could, under specific conditions, allow unauthenticated access to protected management routes. The auth layer derived the effective route from `request.url.path` in `litellm/proxy/auth/auth_utils.py::get_request_route()`, which Starlette reconstructs from the `Host` header. A crafted `Host` could therefore make the auth gate evaluate a different route from the one FastAPI dispatched. Most deployments are not affected. The bypass is blocked by any upstream layer that validates or normalizes `Host`, such as: • a CDN or WAF, such as Cloudflare • a reverse proxy with `server_name` allowlists • a host-based load balancer LiteLLM Cloud customers are not affected. Patches Fixed in `1.84.0`. Upgrade to `1.84.0` or later. No configuration change is required. Workarounds If upgrading is not immediately possible, place the proxy behind an upstream component that validates or normalizes the `Host` header before forwarding (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. References • Patched release: `v1.84.0` Discovery Credit: Le The Thang (KCSC) and Kim Ngoc Chung (One Mount Group)