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Fencer Vulns
low 2.6

CVE-2025-46570 json

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

published 2025-05-28 17 mo ago modified 2026-08-07 3 mo ago also EUVD-2025-16189 , GHSA-4qjh-9fv9-r85r , PYSEC-2025-53

cvss
2.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

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.

Patch / fix

  • pypi vllm 0.9.0
  • vllm-project vllm 0.9.0
  • vllm vllm 0.9.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-46570 updated cvss 2.6

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

  • Red Hat AI Inference Server rhaiis/vllm-cuda-rhel9, rhaiis/vllm-rocm-rhel9 Red Hat Enterprise Linux AI (RHEL AI) rhelai1/ui-rhel9, rhelai1/bootc-amd-rhel9, rhelai1/bootc-intel-rhel9, rhelai1/bootc-nvidia-rhel9, rhelai1/bootc-azure-amd-rhel9, rhelai1/instructlab-amd-rhel9, +5 more
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
17 mo ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 2.6 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
GitHub 3.1 2.6 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
pypi vllm
<0.9.0
0.9.0

Affected products

  • vllm-project vllm

Classification

Weakness
  • CWE-208 Observable Timing Discrepancy
  • CWE-203 Observable Discrepancy

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.