vLLM Authentication Bypass via ASGI Trust (0.3.0-0.22.0)
CVE-2026-48746 Published on June 22, 2026
vLLM: OpenAI auth bypass
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.
Vulnerability Analysis
CVE-2026-48746 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. An automatable proof of concept (POC) exploit exists. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity, and a high impact on availability.
Weakness Types
What is a HTTP Request Smuggling Vulnerability?
When malformed or abnormal HTTP requests are interpreted by one or more entities in the data flow between the user and the web server, such as a proxy or firewall, they can be interpreted inconsistently, allowing the attacker to "smuggle" a request to one device without the other device being aware of it.
CVE-2026-48746 has been classified to as a HTTP Request Smuggling vulnerability or weakness.
Trust Boundary Violation
The product mixes trusted and untrusted data in the same data structure or structured message. A trust boundary can be thought of as line drawn through a program. On one side of the line, data is untrusted. On the other side of the line, data is assumed to be trustworthy. The purpose of validation logic is to allow data to safely cross the trust boundary - to move from untrusted to trusted. A trust boundary violation occurs when a program blurs the line between what is trusted and what is untrusted. By combining trusted and untrusted data in the same data structure, it becomes easier for programmers to mistakenly trust unvalidated data.
Products Associated with CVE-2026-48746
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Affected Versions
vllm-project vllm:- Version >= 0.3.0, < 0.22.0 is affected.
- Version 1782951012 and below * is unaffected.
- Version 1782951244 and below * is unaffected.
- Version 1782353093 and below * is unaffected.
- Version 1782352847 and below * is unaffected.