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CVE-2026-44223— vLLM: extract_hidden_states speculative decoding crashes server on any request with penalty parameters

Quick assessment

Affected
vllm-project vllm
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

vLLM是vLLM开源的一个适用于 LLM 的高吞吐量和内存高效推理和服务引擎。 vLLM 0.20.0之前版本存在安全漏洞，该漏洞源于extract_hidden_states推测解码提议器在第一次解码步骤后返回形状不正确的张量，导致RuntimeError崩溃EngineCore进程，当任何请求使用采样惩罚参数时触发。

CVSS 6.5 · Medium EPSS 0.43% · P35

Affected Version Matrix 1

VendorProduct Version RangeStatus
vllm-project vllm >= 0.18.0, < 0.20.0 affected
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I. Basic Information for CVE-2026-44223

Vulnerability Information
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Vulnerability Title
vLLM: extract_hidden_states speculative decoding crashes server on any request with penalty parameters
Source: CVE Program / CVE List V5
Vulnerability Description
vLLM is an inference and serving engine for large language models (LLMs). From 0.18.0 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
缓冲区大小计算不正确
Source: CVE Program / CVE List V5
Vulnerability Title
vLLM 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
vLLM是vLLM开源的一个适用于 LLM 的高吞吐量和内存高效推理和服务引擎。 vLLM 0.20.0之前版本存在安全漏洞，该漏洞源于extract_hidden_states推测解码提议器在第一次解码步骤后返回形状不正确的张量，导致RuntimeError崩溃EngineCore进程，当任何请求使用采样惩罚参数时触发。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
vllm-project vllm >= 0.18.0, < 0.20.0 -

II. Public POCs for CVE-2026-44223

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III. Intelligence Information for CVE-2026-44223

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Patches & Fixes for CVE-2026-44223 (1)

Vendor Advisories for CVE-2026-44223 (1)

IV. Related Vulnerabilities

Same product: vllm
Same vendor: vllm-project
Same weakness: CWE-131

V. Comments for CVE-2026-44223

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