Starlette Vulnerability Exposes AI Agent Endpoints
A critical vulnerability tracked as CVE-2026-48710 and nicknamed "BadHost" was disclosed in the Starlette ASGI framework, affecting all versions prior to 1.0.1, sources report (Ars Technica, KuCoin). The flaw lets an attacker manipulate the HTTP Host header so the framework reconstructs and reparses request URLs incorrectly, enabling a trivial, unauthenticated path-based authentication bypass (KuCoin, Ars Technica, itsecuritynews.info). Starlette is a foundational dependency for FastAPI and many LLM-serving stacks; Ars Technica and KuCoin note the library reportedly receives 325 million downloads per week, creating a large transitive blast radius that includes vLLM, LiteLLM, MCP servers, and other inference/agent tooling. Patches were released in Starlette 1.0.1 and a free scanner is available at badhost.org, per multiple reports.
