mdast-util-to-hast unsanitized class attribute
Priority LOW 36CWE-20Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Tampering
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- Partial Red Hat: 15 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-915.
Summary
mdast-util-to-hast is an mdast utility to transform to hast. From 13.0.0 to before 13.2.1, multiple (unprefixed) classnames could be added in markdown source by using character references. This could make rendered user supplied markdown code elements appear like the rest of the page. This vulnerability is fixed in 13.2.1.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00327 25th percentileScored 2026-11-07
Fix Partial mdast-util-to-hast (syntax-tree): 13.2.1mdast-util-to-hast (npm): 13.2.1Red Hat: 15 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| syntax-tree | mdast-util-to-hast | 13.0.0 to before 13.2.1 | 13.2.1 | Patch available | CNA |
| — | mdast-util-to-hast (npm) | 13.0.0 to before 13.2.1 | 13.2.1 | Patch available | GHSA-4fh9-h7wg-q85m |
- mdast-util-to-hast Vendorsyntax-tree Affected 13.0.0 to before 13.2.1 Fixed in 13.2.1 Patch available CNA
- mdast-util-to-hast (npm) Vendor— Affected 13.0.0 to before 13.2.1 Fixed in 13.2.1 Patch available GHSA-4fh9-h7wg-q85m
Remediation
- Fix · CNA mdast-util-to-hast (syntax-tree) Fixed in 13.2.1
- Fix · GHSA-4fh9-h7wg-q85m mdast-util-to-hast (npm) Fixed in 13.2.1 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Gatekeeper 3 | Affected | No fix yet: Fix deferred |
| Migration Toolkit for Applications 7 | Affected | No fix yet: Fix deferred |
| Migration Toolkit for Applications 8 | Affected | No fix yet: Fix deferred |
| OpenShift Lightspeed | Affected | No fix yet: Fix deferred |
| OpenShift Pipelines | Affected | No fix yet: Fix deferred |
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet: Fix deferred |
| Red Hat Developer Hub 1 | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Enterprise Application Platform 8 | Affected | No fix yet: Fix deferred |
| Red Hat JBoss Enterprise Application Platform Expansion Pack | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat Quay 3 | Affected | No fix yet: Fix deferred |
| Red Hat Satellite 6 | Affected | No fix yet: Fix deferred |
| Red Hat Trusted Profile Analyzer | Affected | No fix yet: Fix deferred |
| Red Hat build of Apache Camel - HawtIO 4 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2025-66400
- 2026-10-03 Alias added: GHSA-4fh9-h7wg-q85m
- 2026-10-27 Affected versions changed · Red Hat
References
Patch 2
Advisory 2
Sources
- CVE-2025-66400 · CVE Program
- CVE-2025-66400 · NVD
- FIRST EPSS
- GHSA-4fh9-h7wg-q85m · GitHub Advisory Database · CC BY 4.0
- CVE-2025-66400 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences