---
id: CVE-2026-100647
title: >-
  vLLM versions before 0.29.0 contain a denial-of-service vulnerability in the
  cache_salt parameter accepted on OpenAI-compatible and Anthropic API
  endpoints, which lacks maximum length validation and is processed on the
  single EngineCore …
summary: >-
  vLLM versions before 0.29.0 contain a denial-of-service vulnerability in the
  cache_salt parameter accepted on OpenAI-compatible and Anthropic API
  endpoints, which lacks maximum length validation and is processed on the
  single EngineCore …
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-20
  - CWE-1322
vendor: vllm-project
product: vllm
affected:
  - vllm < 0.29.0
published: '2026-09-26'
updated: '2026-09-26'
sourceUpdated: '2026-09-26T14:16:47.097'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100647'
references:
  - url: >-
      https://github.com/vllm-project/vllm/security/advisories/GHSA-wpww-v874-ph2p
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/vllm-before-0.29.0-cpu-exhaustion-via-unbounded-cache-salt
    label: disclosure@vulncheck.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100647.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-100647'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2541900'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-100647'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100647'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ingestedAt: '2026-09-26T13:33:20.921Z'
---

## Overview

vLLM versions before 0.29.0 contain a denial-of-service vulnerability in the cache_salt parameter accepted on OpenAI-compatible and Anthropic API endpoints, which lacks maximum length validation and is processed on the single EngineCore scheduler thread. Unauthenticated attackers can send HTTP requests with multi-hundred-megabyte salt values that trigger expensive pickle serialization and SHA-256 hashing, stalling the scheduler thread and denying service to all concurrent requests.

## Remediation

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

## Vendor advisories

- **Red Hat VEX** · Moderate · 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 2026-09-26 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-100647.json)