---
id: CVE-2026-94623
title: >-
  vLLM through 0.29.0 contains a denial of service vulnerability in the NIXL
  connector's prefix caching implementation that fails to properly validate
  block counts across multi-prompt completion requests in prefill/decode
  disaggregated dep…
summary: >-
  vLLM through 0.29.0 contains a denial of service vulnerability in the NIXL
  connector's prefix caching implementation that fails to properly validate
  block counts across multi-prompt completion requests in prefill/decode
  disaggregated dep…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-617
vendor: vllm-project
product: vllm
affected:
  - vllm <= 0.29.0
published: '2026-09-21'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T20:25:55.870'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-94623'
references:
  - url: 'https://github.com/vllm-project/vllm'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/vllm-project/vllm/blob/v0.29.0/vllm/distributed/kv_transfer/kv_connector/v1/nixl/base_worker.py#L2642-L2646
    label: disclosure@vulncheck.com
  - url: 'https://github.com/vllm-project/vllm/pull/51505'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/vllm-through-0.29.0-denial-of-service-via-nixl-multi-prompt-assertion-failure
    label: disclosure@vulncheck.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-94623.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-94623'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2537883'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-94623'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-94623'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.0063
epssPercentile: 0.47975
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-22T17:19:44.934826Z'
ingestedAt: '2026-09-21T22:54:37.972Z'
---

## Overview

vLLM through 0.29.0 contains a denial of service vulnerability in the NIXL connector's prefix caching implementation that fails to properly validate block counts across multi-prompt completion requests in prefill/decode disaggregated deployments. Attackers can trigger an assertion failure in NixlBaseConnectorWorker._apply_prefix_caching by submitting completion requests with multiple prompts of varying lengths, causing the decode worker to terminate and become unavailable until restarted.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat AI Inference Server, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI) · no fix planned: Red Hat AI Inference Server, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat OpenShift AI (RHOAI) · updated 2026-09-24 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-94623.json)