CVE-2026-55574
HIGH
MEDIUM
Priority: 0.05
BB Relevance:
78/100
Published: 2026-07-06
Modified: 2026-10-25
First seen: 2026-10-29
Status: active
Attack Surface
Network
Low Complexity
No Auth
No Interaction
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
None
S:
X
AT:
None
VC:
None
VI:
None
VA:
High
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.
Weakness Classification (1)
References & Advisories (3)
Vendor Advisory
Mitigation
Patch
Issue Tracking
Patch