CVE-2026-55574 (GCVE-0-2026-55574)

Vulnerability from cvelistv5 – Published: 2026-07-06 20:05 – Updated: 2026-07-06 20:52
VLAI
Title
vLLM: ReDoS via structured_outputs.regex compiled without timeout in xgrammar and outlines backends
Summary
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.
Severity
8.7 (High)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-06 20:52 UTC
CWE
  • CWE-1333 - Inefficient Regular Expression Complexity
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7868 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
vllm-project vllm Affected: < 0.24.0
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

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