CVE-2025-58446Public exploitNetwork attack vector

Model-provider service interruption via slow grammar optimization

Published Sep 6, 2025 · Updated Sep 8, 2025

Denial of service in MLC XGrammar 0.1.23 allows remote attackers to interrupt model-provider service via a large grammar. Grammar.from_json_schema passes huge enums with repeated references into the 0.1.23 grammar optimizer, which processes them at a very low rate. The issue requires an integrating provider to accept attacker-controlled grammars, and the demonstrated consequence is minutes of parsing that delays normal work.

CVSS severity6.9
Medium
EPSS probability0.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Denial of service in MLC XGrammar 0.1.23 allows remote attackers to interrupt model-provider service via a large grammar. Grammar.from_json_schema passes huge enums with repeated references into the 0.1.23 grammar optimizer, which processes them at a very low rate. The issue requires an integrating provider to accept attacker-controlled grammars, and the demonstrated consequence is minutes of parsing that delays normal work.

The record

CVE
CVE-2025-58446
Published
Sep 6, 2025
Updated
Sep 8, 2025
Vendor
MLC
Product
XGrammar
Classifications
CWE-770, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 6, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 8, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion== 0.1.23, < 0.1.24

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MLC · XGrammarversion== 0.1.23, < 0.1.24

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.9GitHub CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo