What’s Vulnerable › Vulnerabilities

CVE-2025-48943: vLLM allows clients to crash the openai server with invalid regex

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-05-30 · updated 2026-06-17
• Weakness: CWE-248

Description

vLLM is an inference and serving engine for large language models (LLMs). Version 0.8.0 up to but excluding 0.9.0 have a Denial of Service (ReDoS) that causes the vLLM server to crash if an invalid regex was provided while using structured output. This vulnerability is similar to GHSA-6qc9-v4r8-22xg/CVE-2025-48942, but for regex instead of a JSON schema. Version 0.9.0 fixes the issue.

Affected products

• vllm-project vllm: from 0.8.0 before 0.9.0 — fixed in 0.9.0

How to fix

Upgrade to a fixed version: vllm-project vllm 0.9.0. Check the vendor advisory for mitigations.

References

• https://github.com/vllm-project/vllm/commit/08bf7840780980c7568c573c70a6a8db94fd45ff
• https://github.com/vllm-project/vllm/issues/17313
• https://github.com/vllm-project/vllm/pull/17623
• https://github.com/vllm-project/vllm/security/advisories/GHSA-9hcf-v7m4-6m2j

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