CVE-2026-44223Public exploitNetwork attack vector

Authenticated service crash via proposer shape mismatch

Published May 12, 2026 · Updated May 12, 2026

Denial of service in vLLM 0.18.0 through 0.19.1 allows remote authenticated users to crash EngineCore via a request with sampling penalties. The extract_hidden_states proposer returns a two-column sampled-token tensor after the first decode step, but penalty processing expects one column and raises a broadcast-shape RuntimeError. The server must use extract_hidden_states speculative decoding; one request with a repetition, frequency, or presence penalty then causes complete service interruption.

CVSS severity6.5
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in vLLM 0.18.0 through 0.19.1 allows remote authenticated users to crash EngineCore via a request with sampling penalties. The extract_hidden_states proposer returns a two-column sampled-token tensor after the first decode step, but penalty processing expects one column and raises a broadcast-shape RuntimeError. The server must use extract_hidden_states speculative decoding; one request with a repetition, frequency, or presence penalty then causes complete service interruption.

The record

CVE
CVE-2026-44223
Published
May 12, 2026
Updated
May 12, 2026
Vendor
vLLM Project
Product
vLLM
Classifications
CWE-131, CWE-704, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 12, 2026CVE publishedPublication date reported by the CVE source.
  2. May 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.18.0, < 0.20.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

vLLM Project · vLLMversion=>= 0.18.0, < 0.20.0

Published CVSS scores

6.5GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-131Incorrect Calculation of Buffer Size
CWE-704Incorrect Type Conversion or Cast
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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