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CVE-2025-57809

XGrammar affected by Denial of Service by infinite recursion grammars

7.7 HighFix available

CVE-2025-57809 is a high vulnerability (CVSS 7.7) in Mlc-ai Xgrammar, published August 25, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.48%, the 41st percentile. Fixed in xgrammar 0.1.21.

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.48%Up 0.4 points since Aug 26, 2025
90%50%10%1%

What each source reports

CVE List Score used 7.7

XGrammar affected by Denial of Service by infinite recursion grammars

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.

Record
CVE-2025-57809
CVSS 4.0
7.7 HighCVSS: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
Weakness
CWE-674
Updated
2026-11-02
EUVDEUVD-2025-28633 7.7

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.

Record
EUVD-2025-28633
CVSS 4.0
7.7 HighCVSS: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
Updated
2026-11-02
GitHub AdvisoriesGHSA-5cmr-4px5-23pc 7.7

XGrammar affected by Denial of Service by infinite recursion grammars

Summary

This issue: http://github.com/mlc-ai/xgrammar/issues/250 should have it's own security advisory. Since several tools accept and pass user supplied grammars to xgrammar, and it is so easy to trigger it seems like a High.

Record
GHSA-5cmr-4px5-23pc
CVSS 4.0
7.7 HighCVSS: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
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-674
Updated
2026-11-02
NVD 7.7

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.

Record
CVE-2025-57809
CVSS 4.0
7.7 HighCVSS: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
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-674
Updated
2026-11-02
OSV 7.7

XGrammar affected by Denial of Service by infinite recursion grammars

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.

Record
CVE-2025-57809
CVSS 4.0
7.7 HighCVSS: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
Weakness
CWE-674
Updated
2026-11-02
OSVGHSA-5cmr-4px5-23pc 7.7

XGrammar affected by Denial of Service by infinite recursion grammars

Summary

This issue: http://github.com/mlc-ai/xgrammar/issues/250 should have it's own security advisory. Since several tools accept and pass user supplied grammars to xgrammar, and it is so easy to trigger it seems like a High.

Record
GHSA-5cmr-4px5-23pc
CVSS 4.0
7.7 HighCVSS: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
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-674
Updated
2026-11-02
OSVPYSEC-2026-2054 7.7

XGrammar affected by Denial of Service by infinite recursion grammars

Summary

This issue: http://github.com/mlc-ai/xgrammar/issues/250 should have it's own security advisory. Since several tools accept and pass user supplied grammars to xgrammar, and it is so easy to trigger it seems like a High.

Record
PYSEC-2026-2054
CVSS 4.0
7.7 HighCVSS: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
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
xgrammar
PyPI
 before 0.1.21
0.1.21
xgrammar
PyPI
 before 0.1.21, plus listed versions
0.1.00.1.10.1.100.1.110.1.12
Show 9 moreShow less
0.1.130.1.170.1.180.1.190.1.200.1.60.1.70.1.80.1.9
0.1.21
xgrammar
PyPI
 before 0.1.21, plus listed versions
0.1.00.1.10.1.100.1.110.1.12
Show 18 moreShow less
0.1.130.1.140.1.150.1.160.1.170.1.180.1.190.1.20.1.200.1.30.1.40.1.4rc20.1.50.1.5rc10.1.60.1.70.1.80.1.9
0.1.21

History

History
WhenChangedSources
2026-11-02createdCVE List, EUVD, GitHub Advisories, NVD, OSV

References

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