CVE-2025-48942: vllm — Exploit & Fix

Description

vLLM is an inference and serving engine for large language models (LLMs). In versions 0.8.0 up to but excluding 0.9.0, hitting the /v1/completions API with a invalid json_schema as a Guided Param kills the vllm server. This vulnerability is similar GHSA-9hcf-v7m4-6m2j/CVE-2025-48943, but for regex instead of a JSON schema. Version 0.9.0 fixes the issue.

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CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-248 CWE-248

Affected Products

Vendor	Product	Versions
vllm	vllm	0.8.0 — 0.9.0

References

Advisories & Patches

https://github.com/vllm-project/vllm/commit/08bf7840780980c7568c573c70a6a8db94fd45ff https://github.com/vllm-project/vllm/pull/17623 https://github.com/vllm-project/vllm/security/advisories/GHSA-6qc9-v4r8-22xg

Exploits

https://github.com/vllm-project/vllm/security/advisories/GHSA-6qc9-v4r8-22xg

Other References

https://github.com/vllm-project/vllm/issues/17248

Frequently Asked Questions

What is CVE-2025-48942? +

vLLM is an inference and serving engine for large language models (LLMs). In versions 0.8.0 up to but excluding 0.9.0, hitting the /v1/completions API with a invalid json_schema as a Guided Param kills the vllm server. This vulnerability is similar GHSA-9hcf-v7m4-6m2j/CVE-2025-48943, but for regex instead of a JSON schema. Version 0.9.0 fixes the issue. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2025-48942? +

CVE-2025-48942 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-48942? +

CVE-2025-48942 affects products from vllm, specifically: vllm. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-48942? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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