CVE-2025-58446

xgrammar vulnerable to denial of service by huge enum grammar

xgrammar is an open-source library for efficient, flexible, and portable structured generation. A grammar optimizer introduced in 0.1.23 processes large grammars (>100k characters) at very low rates, and can be used for DOS of model providers. This issue is fixed in version 0.1.24.

Affected

mlc-ai · xgrammar

CVSS v4.0 GITHUB

6.9 MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1 NVD

7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.62% chance of exploitation in the next 30 days, 49th percentile

Published

2025-09-06

Updated

2025-09-08

Proof-of-concept exploits (2)

• mlc-ai/xgrammar/security/advisories/GHSA-9q5r-wfvf-rr7f
• advisories/GHSA-9q5r-wfvf-rr7f

Security advisories

• mlc-ai/xgrammar/commit/ced69c3ad2f8f61b516cc278a342e7c644383e27

References

• CVE Record
• NVD entry