---
id: CVE-2025-48943
aliases:
  - GHSA-9hcf-v7m4-6m2j
  - PYSEC-2025-55
title: vLLM allows clients to crash the openai server with invalid regex
summary: vLLM allows clients to crash the openai server with invalid regex
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'
vendor: vllm
product: vllm
ecosystem: pip
affected:
  - 'vllm >= 0.8.0, < 0.9.0'
patched:
  - vllm 0.9.0
published: '2025-05-28'
updated: '2026-08-07'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-9hcf-v7m4-6m2j'
references:
  - url: >-
      https://github.com/vllm-project/vllm/security/advisories/GHSA-9hcf-v7m4-6m2j
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-48943'
  - url: 'https://github.com/vllm-project/vllm/issues/17313'
  - url: 'https://github.com/vllm-project/vllm/pull/17623'
  - url: >-
      https://github.com/vllm-project/vllm/commit/08bf7840780980c7568c573c70a6a8db94fd45ff
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/vllm/PYSEC-2025-55.yaml
  - url: 'https://github.com/vllm-project/vllm'
tags:
  - osv
  - pip
epss: 0.00475
epssPercentile: 0.40249
ingestedAt: '2026-08-07T19:14:14.172Z'
---

## Overview

### Impact

A denial of service bug caused the vLLM server to crash if an invalid regex was provided while using structured output. This vulnerability is similar to [GHSA-6qc9-v4r8-22xg](https://github.com/vllm-project/vllm/security/advisories/GHSA-6qc9-v4r8-22xg), but for regex instead of a JSON schema.

Issue with more details: https://github.com/vllm-project/vllm/issues/17313

### Patches

* https://github.com/vllm-project/vllm/pull/17623

## Affected packages

- `vllm >= 0.8.0, < 0.9.0`

## Remediation

Upgrade to a patched release:

- `vllm 0.9.0`