Security Digest · Vulnerability record
CVE-2026-48746: vLLM: OpenAI auth bypass
vLLM is an inference and serving engine for large language models (LLMs).
CVSS 9.1 Critical EPSS 1.2% · p67
Should you act?
Critical and remotely reachable
No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 1.2%, percentile 67: FIRST’s model estimates a 1.2% chance of exploitation activity in the next 30 days, higher than 67% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes
vllm(PyPI) >= 0.3.0, < 0.22.0, fixed in 0.22.0. Check your lockfile, including transitive dependencies.
What it is
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 VLLMAPIKEY or --api-key. This vulnerability is fixed in 0.22.0.
From the GitHub advisory
Summary
A vulnerability in ASGI web servers and starlette's trust on those web servers enables an authentication bypass of the OpenAI API AuthenticationMiddleware, which was discovered during @x41sec's source code audit. It allows to use the API without providing the configured VLLMAPIKEY or --api-key.
Details
In https://github.com/vllm-project/vllm/blob/v0.14.0/vllm/entrypoints/openai/apiserver.py#L689-L692 the urlpath is taken from the URL, which is reconstructed by starlette based on the request scope.
The request scope includes the request's Host: header and reconstructs the URL as shown below:
Weakness type: CWE-444, CWE-501.
Product: vllm (PyPI) · Assigned by: GitHub_M · Published: 2026-06-22
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| PyPI | vllm | >= 0.3.0, < 0.22.0 | 0.22.0 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| vllm-project | vllm | >= 0.3.0, < 0.22.0 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H |
| redhat-SADP | 3.1 | 9.1 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H |
| GitHub | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: none (no login)
- User interaction: none
- Scope: unchanged
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable yes, technical impact partial.
- FIRST EPSS (model of 2026-10-21): 1.15% probability of exploitation activity in the next 30 days; percentile 67.
Timeline
- — GitHub-reviewed advisory GHSA-94f4-hr76-p5j6 published (critical)
- — CVE record published by GitHub_M
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
Vulnerability records
- GitHub Advisory GHSA-94f4-hr76-p5j6 github.com
- CVE.org record CVE-2026-48746 cve.org
- NVD entry CVE-2026-48746 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- github.com github.com
- x41-dsec.de x41-dsec.de
- access.redhat.com access.redhat.com
- RHBZ#2491581 bugzilla.redhat.com
- security.access.redhat.com security.access.redhat.com
- github.com github.com