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CVE Record

CVE-2026-25048: xgrammar: Multi-layer nesting causes DoS

xgrammar is an open-source library for efficient, flexible, and portable structured generation. Prior to version 0.1.32, the multi-level nested syntax caused a segmentation fault (core dumped). This issue has been patched in version 0.1.32.

HighCVSS 8.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-25048 is a denial-of-service flaw in mlc-ai xgrammar before 0.1.32. Specially nested syntax can crash the library with a segmentation fault, interrupting applications that rely on it for structured generation. The published evidence names availability impact, not data theft or privilege gain.

Executive priority

Prioritize remediation for production services using xgrammar, especially externally reachable AI or structured-generation workflows. The main business risk is service disruption, not confirmed data compromise. Patch promptly, but avoid emergency breach assumptions without additional evidence.

Technical view

The issue is classified as CWE-674 and affects xgrammar versions before 0.1.32. Multi-level nested syntax can trigger a segmentation fault and core dump. CVSS 4.0 is 8.7 with network, low-complexity, no-auth, no-user-interaction characteristics and high vulnerable-system availability impact.

Likely exposure

Exposure is likely where applications or services use mlc-ai xgrammar below 0.1.32, especially if they process user-controlled grammar or structured-generation syntax. Red Hat advisories are listed, so packaged deployments should verify vendor applicability rather than assuming upstream-only exposure.

Exploitation context

The bundle does not show CISA KEV listing or confirmed active exploitation. The advisory describes a crash condition rather than exploit code. Treat internet-facing or multi-tenant parsing paths as higher urgency because unauthenticated input may affect service availability.

Researcher notes

Sources identify the trigger class as multi-layer nesting and the failure mode as segmentation fault. Public details in the bundle do not establish precise parser internals, exploit circulation, or downstream product impact beyond listed xgrammar and Red Hat tracking references.

Mitigation direction

  • Upgrade mlc-ai xgrammar to version 0.1.32 or later.
  • Apply relevant Red Hat errata where xgrammar is vendor-packaged.
  • Limit untrusted nested syntax input until fixed.
  • Review vendor guidance for environment-specific remediation details.
  • Monitor affected services for crashes or core dumps.

Validation and detection

  • Inventory SBOMs, lockfiles, images, and runtimes for xgrammar.
  • Confirm deployed xgrammar versions are 0.1.32 or later.
  • Check logs for segmentation faults or unexplained parser crashes.
  • Verify Red Hat advisory applicability for managed packages.
  • Run non-destructive resilience tests against structured-generation parsing paths.
Prepared
Confidence
high
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-674: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-25048 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
8.7 (4.0)
Known Exploited
No
Published

Vector: 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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
11Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.7CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N——GitHub_M
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 4.0 score

8.7High
CVSS 4.0 vector shape for CVE-2026-25048Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: 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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPxgrammar: xgrammar: Denial of Service via multi-level nested syntax
other:Red Hat severity ratingcvssV3_1
  • 2026-03-05T16:01:14.634Z: Reported to Red Hat.
  • 2026-03-05T15:34:42.095Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
mlc-aixgrammar< 0.1.32Listed
Weakness

CWE details

CWE-674

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-674 · source CWE mapping

Uncontrolled Recursion

Uncontrolled Recursion represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs