---
id: CVE-2026-100654
title: >-
  vLLM before 0.29.0 accepts user-controlled stop_token_ids on the
  OpenAI-compatible POST /v1/completions and POST /v1/chat/completions endpoints
  but validates only that the values are integers, not that each token id is
  within the model v…
summary: >-
  vLLM before 0.29.0 accepts user-controlled stop_token_ids on the
  OpenAI-compatible POST /v1/completions and POST /v1/chat/completions endpoints
  but validates only that the values are integers, not that each token id is
  within the model v…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-129
vendor: vllm-project
product: vllm
affected:
  - vllm < 0.29.0
published: '2026-09-26'
updated: '2026-09-26'
sourceUpdated: '2026-09-26T14:16:48.100'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100654'
references:
  - url: >-
      https://github.com/vllm-project/vllm/security/advisories/GHSA-v5gm-qgmv-gc6c
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/vllm-before-0.29.0-denial-of-service-via-out-of-range-stop-token-ids
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-26T13:33:20.917Z'
---

## Overview

vLLM before 0.29.0 accepts user-controlled stop_token_ids on the OpenAI-compatible POST /v1/completions and POST /v1/chat/completions endpoints but validates only that the values are integers, not that each token id is within the model vocabulary/logits range. When min_tokens > 0, the stop token ids are used as logits indices to suppress stop tokens, so an out-of-range id reaches a CUDA indexing operation (index_put_) and triggers a device-side assertion. An authenticated API user can send a single malformed completion request that returns 500 Internal Server Error and puts EngineCore into a fatal state, causing subsequent requests to fail until the service is restarted (denial of service).

## Remediation

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