Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Vllm | Vllm | < 0.24.0 |
Related Weaknesses (CWE)
References
- https://github.com/vllm-project/vllm/commit/2b3006076c5e9bc4cda9e03e3641388de3c5Patch
- https://github.com/vllm-project/vllm/pull/45118Issue TrackingPatch
- https://github.com/vllm-project/vllm/security/advisories/GHSA-rwxx-mrjm-wc2mVendor AdvisoryMitigation
FAQ
What is CVE-2026-55574?
CVE-2026-55574 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 direc...
How severe is CVE-2026-55574?
CVE-2026-55574 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-55574?
Check the references section above for vendor advisories and patch information. Affected products include: Vllm Vllm.