--- id: CVE-2025-57809 title: >- xgrammar: XGrammar affected by Denial of Service by infinite recursion grammars (CVE-2025-57809) summary: >- A flaw was found in xgrammar. Recursive grammar definitions could trigger infinite recursion during parsing in GrammarMatcherBase::ExpandEquivalentStackElements, leading to unbounded stack growth and a segmentation fault. This vulnerabilit… severity: high cvss: 7.5 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H' cvssSource: vendor cwe: CWE-674 vendor: Red Hat product: Red Hat Enterprise Linux AI 1.5 affected: - ai_inference_server - enterprise_linux_ai 1.5 patched: - enterprise_linux_ai 1.5 published: '2025-08-25' updated: '2026-09-21' sourceUpdated: '2026-09-21T15:58:24+00:00' source: CSAF sourceUrl: 'https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-57809.json' references: - url: >- https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-57809.json - url: 'https://access.redhat.com/security/cve/CVE-2025-57809' - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2390943' - url: 'https://www.cve.org/CVERecord?id=CVE-2025-57809' - url: 'https://nvd.nist.gov/vuln/detail/CVE-2025-57809' - url: >- https://github.com/mlc-ai/xgrammar/commit/b943feacb5a1caf4d39de8ec3bf7c7ce066dcee5 - url: 'https://github.com/mlc-ai/xgrammar/issues/250' - url: 'https://github.com/mlc-ai/xgrammar/security/advisories/GHSA-5cmr-4px5-23pc' - url: 'https://access.redhat.com/errata/RHSA-2025:19427' - url: 'https://access.redhat.com/errata/RHSA-2025:19429' - url: 'https://access.redhat.com/errata/RHSA-2025:19424' - url: 'https://access.redhat.com/errata/RHSA-2025:19430' - url: 'https://access.redhat.com/errata/RHSA-2025:19426' - url: 'https://access.redhat.com/errata/RHSA-2025:19422' - url: 'https://access.redhat.com/errata/RHSA-2025:19428' - url: 'https://access.redhat.com/errata/RHSA-2025:19425' - url: 'https://access.redhat.com/errata/RHSA-2025:19421' - url: 'https://access.redhat.com/errata/RHSA-2025:19423' - url: 'https://github.com/mlc-ai/xgrammar' tags: - csaf - vex - red-hat - osv - pip epss: 0.00466 epssPercentile: 0.39536 aliases: - GHSA-5cmr-4px5-23pc - PYSEC-2026-2054 ecosystem: pip ingestedAt: '2026-07-08T18:25:45.969Z' --- ## Overview A flaw was found in xgrammar. Recursive grammar definitions could trigger infinite recursion during parsing in GrammarMatcherBase::ExpandEquivalentStackElements, leading to unbounded stack growth and a segmentation fault. This vulnerability allows remote attackers to cause a denial of service (DoS) when untrusted grammar is processed. ## Vendor advisories - **RHSA-2025:19427** · Red Hat · fixed in: Red Hat Enterprise Linux AI 1.5 · released 2025-11-03 · [advisory](https://access.redhat.com/errata/RHSA-2025:19427) - **RHSA-2025:19429** · Red Hat · fixed in: Red Hat Enterprise Linux AI 1.5 · released 2025-11-03 · [advisory](https://access.redhat.com/errata/RHSA-2025:19429) - **RHSA-2025:19424** · Red Hat · fixed in: Red Hat Enterprise Linux AI 1.5 · released 2025-11-03 · [advisory](https://access.redhat.com/errata/RHSA-2025:19424) - **RHSA-2025:19430** · Red Hat · fixed in: Red Hat Enterprise Linux AI 1.5 · released 2025-11-03 · [advisory](https://access.redhat.com/errata/RHSA-2025:19430) - **RHSA-2025:19426** · Red Hat · fixed in: Red Hat Enterprise Linux AI 1.5 · released 2025-11-03 · [advisory](https://access.redhat.com/errata/RHSA-2025:19426) - **RHSA-2025:19422** · Red Hat · fixed in: Red Hat Enterprise Linux AI 1.5 · released 2025-11-03 · [advisory](https://access.redhat.com/errata/RHSA-2025:19422) - **RHSA-2025:19428** · Red Hat · fixed in: Red Hat Enterprise Linux AI 1.5 · released 2025-11-03 · [advisory](https://access.redhat.com/errata/RHSA-2025:19428) - **RHSA-2025:19425** · Red Hat · fixed in: Red Hat Enterprise Linux AI 1.5 · released 2025-11-03 · [advisory](https://access.redhat.com/errata/RHSA-2025:19425) - **RHSA-2025:19421** · Red Hat · fixed in: Red Hat Enterprise Linux AI 1.5 · released 2025-11-03 · [advisory](https://access.redhat.com/errata/RHSA-2025:19421) - **RHSA-2025:19423** · Red Hat · fixed in: Red Hat Enterprise Linux AI 1.5 · released 2025-11-03 · [advisory](https://access.redhat.com/errata/RHSA-2025:19423) - **Red Hat VEX** · Important · affected: Red Hat AI Inference Server · no fix planned: Red Hat AI Inference Server · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-57809.json) **xgrammar: XGrammar affected by Denial of Service by infinite recursion grammars** — rated Important by Red Hat. Released 2025-08-25, updated 2026-09-21. Affected: - Red Hat AI Inference Server Fixed: - Red Hat Enterprise Linux AI 1.5 No fix planned: - Red Hat AI Inference Server ## Remediation For more information visit https://access.redhat.com/errata/RHSA-2025:19427 https://access.redhat.com/errata/RHSA-2025:19427 For more information visit https://access.redhat.com/errata/RHSA-2025:19429 https://access.redhat.com/errata/RHSA-2025:19429 For more information visit https://access.redhat.com/errata/RHSA-2025:19424 https://access.redhat.com/errata/RHSA-2025:19424 Workarounds / mitigations: - Mitigation is either unavailable or does not meet Red Hat Product Security standards for usability, deployment, applicability, or stability. ## Package advisory (CVE-2025-57809) Affected packages: - `xgrammar < 0.1.21` Patched in: - `xgrammar 0.1.21` Source: https://osv.dev/vulnerability/GHSA-5cmr-4px5-23pc