CVE-2025-46570

vLLM’s Chunk-Based Prefix Caching Vulnerable to Potential Timing Side-Channel

Published May 29, 2025 CVSS 3.1 · 2.6 Low EPSS < 1% KEV · Not listed
Description
vLLM is an inference and serving engine for large language models (LLMs). Prior to version 0.9.0, when a new prompt is processed, if the PageAttention mechanism finds a matching prefix chunk, the prefill process speeds up, which is reflected in the TTFT (Time to First Token). These timing differences caused by matching chunks are significant enough to be recognized and exploited. This issue has been patched in version 0.9.0.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2025-16189 vLLM is an inference and serving engine for large language models (LLMs). Prior to version 0.9.0, when a new prompt is processed, if the PageAttention mechanism finds a matching prefix chunk, the prefill process speeds up, which is reflected in the TTFT (Time to First Token). These timing differences caused by matching chunks are significant enough to be recognized and exploited. This issue has been patched in version 0.9.0.
Github GHSA Github GHSA GHSA-4qjh-9fv9-r85r Potential Timing Side-Channel Vulnerability in vLLM’s Chunk-Based Prefix Caching
History
Type Values Removed Values Added
First Time appeared Vllm
Vllm vllm
Weaknesses CWE-203
CPEs cpe:2.3:a:vllm:vllm:*:*:*:*:*:*:*:*
Vendors & Products Vllm
Vllm vllm
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description vLLM is an inference and serving engine for large language models (LLMs). Prior to version 0.9.0, when a new prompt is processed, if the PageAttention mechanism finds a matching prefix chunk, the prefill process speeds up, which is reflected in the TTFT (Time to First Token). These timing differences caused by matching chunks are significant enough to be recognized and exploited. This issue has been patched in version 0.9.0.
Title vLLM’s Chunk-Based Prefix Caching Vulnerable to Potential Timing Side-Channel
Weaknesses CWE-208
References
Metrics cvssV3_1

{'score': 2.6, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
May 29, 2025, 6:05 PM
Reserved
Apr 24, 2025, 9:10 PM
Status
Analyzed
Published
May 29, 2025, 5:15 PM
Modified
Jun 17, 2026, 9:26 AM
Severity
Low
Public date
May 29, 2025, 4:32 PM