CVE-2026-55574: vLLM is a high-throughput and memory-efficient inference and serving engine for LLMs. Prior to 0.24.0, the structured_outputs.regex API parameter passes a user-supplied regular exp

highCVSS 7.5CVE-2026-55574

vLLM is a high-throughput and memory-efficient inference and serving engine for LLMs. Prior to 0.24.0, the structured_outputs.regex API parameter passes a user-supplied regular expression string directly to the grammar compiler backends with no compilation timeout; in the xgrammar backend the string reaches the regex compiler with no guard, and in the outlines backend the validation step blocks structural issues such as lookarounds and backreferences but performs no complexity analysis, so a pattern with nested quantifiers passes all checks and causes exponential state-space expansion, allowing a single request containing an adversarial regex to hang an inference worker indefinitely and deny service. This issue is fixed in version 0.24.0.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: high — CVSS 7.5
Published: 2026-07-06
Last updated: 2026-07-07
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-55574

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-555740.32% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 24% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-55574	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

medium[NEW] [medium] vllm: Multiple vulnerabilities allow Denial of Servicecert-bund

Recent advisories for vLLM is a

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

high[UPDATE] [high] vllm: Vulnerability allows code executioncert-bund · 2026-07-10
medium[NEW] [medium] vllm: Multiple vulnerabilities allow Denial of Servicecert-bund · 2026-07-07
high[UPDATE] [high] vllm: Vulnerability allows bypassing security measurescert-bund · 2026-07-07
medium[UPDATE] [medium] vllm: Vulnerability allows code executioncert-bund · 2026-07-07
medium[UPDATE] [medium] vllm: Multiple vulnerabilitiescert-bund · 2026-07-07
medium[UPDATE] [medium] vllm: Multiple vulnerabilitiescert-bund · 2026-07-07