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Fencer Intel
high 7.5

CVE-2025-57809 json

XGrammar affected by Denial of Service by infinite recursion grammars

published last yr. modified last mo. also GHSA-5cmr-4px5-23pc , PYSEC-2026-2054 , EUVD-2025-28633

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

XGrammar is an open-source library for efficient, flexible, and portable structured generation. Prior to version 0.1.21, XGrammar has an infinite recursion issue in the grammar. This issue has been resolved in version 0.1.21.

Patch / fix

  • pypi xgrammar 0.1.21
  • mlc-ai xgrammar 0.1.21

Is CVE-2025-57809 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-57809 updated cvss 7.5

xgrammar: XGrammar affected by Denial of Service by infinite recursion grammars

  • Red Hat AI Inference Server rhaiis/vllm-cuda-rhel9, rhaiis/vllm-rocm-rhel9
    affected: workaround, no fix available “Mitigation is either unavailable or does not meet Red Hat Product Security standards for usability, deployment, applicability, or stability.”
  • Red Hat Enterprise Linux AI 1.5 rhelai1 1.5.4-1761043227, rhelai1 1.5.4-1761050413, rhelai1 1.5.4-1761060689, rhelai1 1.5.4-1761064179, rhelai1 1.5.4-1761073793, rhelai1 1.5.4-1761220254, +4 more
    fixed: vendor fix “Mitigation is either unavailable or does not meet Red Hat Product Security standards for usability, deployment, applicability, or stability.” RHSA-2025:19427

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/mlc-ai/xgrammar/issues/250 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 7.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P
CNA 4.0 7.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/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
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi xgrammar
<0.1.21
0.1.21

Affected products

  • mlc-ai xgrammar

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.