CVE-2025-32381: XGrammar is an open-source library for efficient, flexible, and portable structured generation

Q: How do I fix CVE-2025-32381?

xgrammar: upgrade to 0.1.18. Exact commands for each OS are on this page.

Q: Is CVE-2025-32381 being exploited?

CVE-2025-32381 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-32381 affect?

CVE-2025-32381 affects xgrammar. Severity is medium (CVSS 6.5). XGrammar is an open-source library for efficient, flexible, and portable structured generation. Prior to 0.1.18, Xgrammar includes a cache for compiled grammars to increase performance with repeated use of the same grammar. This cache is he

Q: How urgent is CVE-2025-32381?

Priority 34/100. No elevated risk signals yet.

Routine

MEDIUM 6.5UPGRADE

CVE-2025-32381 is a medium-severity flaw (CVSS 6.5) affecting xgrammar. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

XGrammar is an open-source library for efficient, flexible, and portable structured generation. Prior to 0.1.18, Xgrammar includes a cache for compiled grammars to increase performance with repeated use of the same grammar. This cache is held in memory. Since the cache is unbounded, a system making use of xgrammar can be abused to fill up a host's memory and case a denial of service. For example, sending many small requests to an LLM inference se

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.5% (top 57%)
CISA exploited list	No
Weakness	CWE-770
Published	2025-04-09
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: mlc-ai

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-04-09 16:15 UTCPublished CVE record published
2026-06-17 09:11 UTCUpdated Record last modified

mlc-ai xgrammar UPGRADE

Affected: < 0.1.18

Fixed in: 0.1.18

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy xgrammar || rpm -q xgrammar || xgrammar --version

2. UPGRADE to 0.1.18 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade xgrammar

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade xgrammar

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-32381?

xgrammar: upgrade to 0.1.18. Exact commands for each OS are on this page.

Is CVE-2025-32381 being exploited?

CVE-2025-32381 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-32381 affect?

CVE-2025-32381 affects xgrammar. Severity is medium (CVSS 6.5). XGrammar is an open-source library for efficient, flexible, and portable structured generation. Prior to 0.1.18, Xgrammar includes a cache for compiled grammars to increase performance with repeated use of the same grammar. This cache is he

How urgent is CVE-2025-32381?

Priority 34/100. No elevated risk signals yet.

Related CVEs

CVE-2026-25048 HIGH 7.5 UPGRADE xgrammar is an open-source library for efficient, flexible, and portable structured generation
CVE-2025-58446 HIGH 7.5 DOWNGRADE xgrammar is an open-source library for efficient, flexible, and portable structured generation
CVE-2025-57809 HIGH 7.5 UPGRADE XGrammar is an open-source library for efficient, flexible, and portable structured generation

References

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