CVE-2026-48746

Critical [CVE-2026-48746] Critical authentication bypass allows unauthorized API access

CVE-2026-48746Source published Jun 22, 2026Source updated Jun 22, 2026

vLLM is an inference and serving engine for large language models (LLMs). From 0.3.0 until 0.22.0, a vulnerability in ASGI web servers and starlette's trust on those web servers enables an authentication bypass of the OpenAI API AuthenticationMiddleware. It allows to use the API without providing the configured VLLM_API_KEY or --api-key. This vulnerability is fixed in 0.22.0. CVE-2026-48746 is an authentication bypass in the vLLM OpenAI-compatible API server. A remote attacker who can reach the vLLM endpoint directly can craft a Host header so the authentication middleware checks a different URL path than the one actually dispatched, bypassing VLLM_API_KEY / --api-key protection. Successful exploitation allows unauthorized inference API access, which can result in confidentiality loss…

Affected products in this advisory

• Red Hat AI Inference Server 3.2
• Red Hat AI Inference Server 3.3
• Red Hat AI Inference Server 3.4
• Red Hat Ansible Automation Platform 2.6

7 more entries in the full advisory.

Source-reported affected versions

Affected-version details not available in this record.

Source-reported fixed versions

• 0.22.0
• rhaiis/vllm-cuda-rhel9:1782951012
• rhaiis/vllm-rocm-rhel9:1782951244
• rhaiis/vllm-cuda-rhel9:1787860580

25 more entries in the full advisory.

Mitigation guidance

• Restrict network access to the vLLM API endpoint to only trusted clients and internal networks. Implement firewall rules or network policies to limit inbound connections to the vLLM service, thereby reducing the attack surface. This operational control helps prevent unauthorized external access to the vulnerable API.