2026-06-22 · 2026-Q2
vLLM OpenAI-Compatible API Authentication Bypass (CVE-2026-48746)
PrimaryL6Identity / Run
- Fixable:
- Yes, vendor patch
- Vendor response:
- Patched
- In the wild:
- No
- Actor:
- Attacker
Target
vLLM OpenAI-compatible API server, versions 0.3.0 through 0.21.x (fixed in 0.22.0)
Impact
A remote attacker bypasses API-key authentication and reaches protected inference endpoints without a valid `VLLM_API_KEY` or `--api-key`
Root Cause
`AuthenticationMiddleware.__call__` reconstructed the request path with `URL(scope=scope).path`, which trusts the unsanitized `Host` header; a crafted `Host: localhost/v1/models?` manipulates the path so the `/v1` auth check fails open. The fix uses `scope["path"]` directly