CVE-2026-48746: vLLM is an inference and serving engine for large language models (LLMs)

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CRITICAL 9.1REMOTEUPGRADE

CVE-2026-48746 is a critical-severity flaw (CVSS 9.1) affecting vllm. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Critical severity
CISA SSVC: public proof of concept
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 33%)
CISA exploited list	No
Weakness	CWE-444, CWE-501
Published	2026-06-22
Last modified	2026-10-25

Publisher (CNA): GitHub, Inc. · Vendor: vllm

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-22 23:16 UTCPublished CVE record published
2026-10-25 23:10 UTCUpdated Record last modified

vllm vllm UPGRADE

Affected: >= 0.3.0 and < 0.22.0

Fixed in: 0.22.0

Safe to downgrade to: a release before 0.3.0

1. Check installed version

apt-cache policy vllm || rpm -q vllm || vllm --version

2. UPGRADE to 0.22.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade vllm

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade vllm

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 0.3.0 (Debian / Ubuntu)

apt-cache madison vllm sudo apt install vllm=<VERSION_BEFORE_0.3.0> sudo apt-mark hold vllm

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list vllm sudo dnf downgrade vllm-<VERSION_BEFORE_0.3.0> sudo dnf versionlock add vllm

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Python (pip) · vllm · FIXED · 0.22.0 · vulnerable: >= 0.3.0, < 0.22.0 · source

pip install --upgrade "vllm>=0.22.0" pip show vllm

Fedora 46 · mingw-qt5-qtwebkit · FIXED · 5.212.0-0.46.alpha4.fc46 · FEDORA-2026-46ae541c22 · source

sudo dnf upgrade --advisory=FEDORA-2026-46ae541c22

Fedora ELN · kdominate · FIXED · 26.08.2-2.eln159 · FEDORA-2026-b1d98239fd · source

sudo dnf upgrade --advisory=FEDORA-2026-b1d98239fd

RHEL AI (RHEL AI) 3 · rhelai3/bootc-gaudi-rhel9 · DEFERRED

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: x41-dsec.de/lab/advisories/x41-2026-002-starlette

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-48746?

vllm: upgrade to 0.22.0. Exact commands for each OS are on this page.

Is CVE-2026-48746 being exploited?

CVE-2026-48746 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-48746 affect?

CVE-2026-48746 affects vllm. Severity is critical (CVSS 9.1). 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 Authenticat

How urgent is CVE-2026-48746?

Priority 57/100. Critical severity; CISA SSVC: public proof of concept; Remotely exploitable, no login, no user action

Software pages

OpenAI and LLM tools vulnerabilities

Related CVEs

CVE-2026-54232 HIGH 8.8 UPGRADE vLLM is an inference and serving engine for large language models (LLMs)
CVE-2026-41523 HIGH 7.5 UPGRADE vLLM is an inference and serving engine for large language models (LLMs)
CVE-2026-54236 MEDIUM 5.3 UPGRADE vLLM is an inference and serving engine for large language models (LLMs)
CVE-2026-53923 HIGH 7.5 UPGRADE vLLM is an inference and serving engine for large language models (LLMs)
CVE-2026-54235 MEDIUM 6.5 UPGRADE vLLM is an inference and serving engine for large language models (LLMs)

References

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