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CVE-2026-55574

CVE-2026-55574 · vLLM: ReDoS via structured_outputs.regex compiled without timeout in xgrammar and outlines backends

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 8.7 · High · EPSS 0.6% · Fix available

Published
Updated

Stack: python

Affected products and versions

  • vllm

    Versions
    • < 0.24.0: Affected

    No fix published

  • vllm PyPI

    Versions
    • 0.0.1
    • 0.1.0
    • 0.1.1
    • 0.1.2
    • 0.1.3
    • 0.1.4
    • 0.1.5
    • 0.1.6
    • 0.1.7
    • 0.10.0
    • 0.10.1
    • 0.10.1.1
    • 0.10.2
    • 0.11.0
    • 0.11.1
    • 0.11.2
    • 0.12.0
    • 0.13.0
    • 0.14.0
    • 0.14.1
    • 0.15.0
    • 0.15.1
    • 0.16.0
    • 0.17.0
    • 0.17.1
    • 0.18.0
    • 0.18.1
    • 0.19.0
    • 0.19.1
    • 0.2.0
    • 0.2.1
    • 0.2.1.post1
    • 0.2.2
    • 0.2.3
    • 0.2.4
    • 0.2.5
    • 0.2.6
    • 0.2.7
    • 0.20.0
    • 0.20.1
    • 0.20.2
    • 0.21.0
    • 0.22.0
    • 0.22.1
    • 0.23.0
    • 0.3.0
    • 0.3.1
    • 0.3.2
    • 0.3.3
    • 0.4.0
    • 0.4.0.post1
    • 0.4.1
    • 0.4.2
    • 0.4.3
    • 0.5.0
    • 0.5.0.post1
    • 0.5.1
    • 0.5.2
    • 0.5.3
    • 0.5.3.post1
    • 0.5.4
    • 0.5.5
    • 0.6.0
    • 0.6.1
    • 0.6.1.post1
    • 0.6.1.post2
    • 0.6.2
    • 0.6.3
    • 0.6.3.post1
    • 0.6.4
    • 0.6.4.post1
    • 0.6.5
    • 0.6.6
    • 0.6.6.post1
    • 0.7.0
    • 0.7.1
    • 0.7.2
    • 0.7.3
    • 0.8.0
    • 0.8.1
    • 0.8.2
    • 0.8.3
    • 0.8.4
    • 0.8.5
    • 0.8.5.post1
    • 0.9.0
    • 0.9.0.1
    • 0.9.1
    • 0.9.2
    Affected ranges
    • ECOSYSTEM: < 0.24.0

    Update to 0.24.0

Original sources

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