CVE-2026-44223

vLLM: extract_hidden_states speculative decoding crashes server on any request with penalty parameters

MEDIUM
6.5
CVSS Score
Published: May 12, 2026 at 07:58 PM UTC
Updated: June 22, 2026 at 11:18 PM UTC
1 product affected across 1 vendorvLLM

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Severity
MEDIUM6.5
Exploit prediction
EPSS 0.4%
SSVC
PoC

Description

vLLM is an inference and serving engine for large language models (LLMs). From to before 0.20.0, the extract_hidden_states speculative decoding proposer in vLLM returns a tensor with an incorrect shape after the first decode step, causing a RuntimeError that crashes the EngineCore process. The crash is triggered when any request in the batch uses sampling penalty parameters (repetition_penalty, frequency_penalty, or presence_penalty). A single request with a penalty parameter (e.g., "repetition_penalty": 1.1) is sufficient to crash the server. This vulnerability is fixed in 0.20.0.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.20.00.18.0 ≤ v < 0.20.0
Affected range stops below 0.20.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (2)

x_refsource_CONFIRMMitigationVendor Advisory
Source: cverecord
https://github.com/vllm-project/vllm/security/advisories/GHSA-83vm-p52w-f9pw
x_refsource_MISCIssue TrackingPatch
Source: cverecord
https://github.com/vllm-project/vllm/pull/38610

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.5MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-131CWE-704

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