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.
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Solution
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References
History
Mon, 06 Jul 2026 22:15:00 +0000
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Mon, 06 Jul 2026 21:30:00 +0000
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Mon, 06 Jul 2026 20:30:00 +0000
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| Description | 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. | |
| Title | vLLM: ReDoS via structured_outputs.regex compiled without timeout in xgrammar and outlines backends | |
| Weaknesses | CWE-1333 | |
| References |
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| Metrics |
cvssV4_0
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-07-06T20:52:57.336Z
Reserved: 2026-06-16T23:11:20.214Z
Link: CVE-2026-55574
Updated: 2026-07-06T20:52:53.852Z
No data.
No data.
OpenCVE Enrichment
Updated: 2026-07-06T22:00:14Z
Weaknesses