Read the docs
TI-2026-38654 Aliases CVE-2026-53597GHSA-c4gh-rv8h-q9vw

Prompty: Arbitrary code execution via JavaScript frontmatter in TypeScript loader

Priority MEDIUM 40CWE-94Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
None
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-94.

Summary

Prompty is a markdown file format (.prompty) for LLM prompts. From 2.0.0-alpha.1 until 2.0.0-beta.3, the @prompty/core TypeScript loader in runtime/typescript/packages/core/src/core/loader.ts used gray-matter without overriding executable js and javascript frontmatter engines, allowing an attacker-controlled .prompty file with ---js frontmatter to execute arbitrary JavaScript during prompt loading. This issue is fixed in version 2.0.0-beta.3.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00972 62nd percentileScored 2026-11-07
Fix Fixed prompty (microsoft): 2.0.0-beta.3@prompty/core (npm): 2.0.0-beta.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Microsoftprompty2.0.0-alpha.1 to before 2.0.0-beta.32.0.0-beta.3Patch availableCNA
—@prompty/core (npm)2.0.0-alpha.1 to before 2.0.0-beta.32.0.0-beta.3Patch availableGHSA-c4gh-rv8h-q9vw
  • prompty VendorMicrosoft Affected 2.0.0-alpha.1 to before 2.0.0-beta.3 Fixed in 2.0.0-beta.3 Patch available CNA
  • @prompty/core (npm) Vendor— Affected 2.0.0-alpha.1 to before 2.0.0-beta.3 Fixed in 2.0.0-beta.3 Patch available GHSA-c4gh-rv8h-q9vw

Remediation

  • Fix · CNA prompty (microsoft) Fixed in 2.0.0-beta.3
  • Fix · GHSA-c4gh-rv8h-q9vw @prompty/core (npm) Fixed in 2.0.0-beta.3 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-53597
  2. 2026-10-03 Alias added: GHSA-c4gh-rv8h-q9vw

References

Advisory 1

Other 3

  • TI-2026-42212 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-37256 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-26194 Windows Internet Key Exchange (IKE) Service Extensions Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-16982 Microsoft SharePoint Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-36863 Windows Server Update Service (WSUS) Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-33671 Microsoft SharePoint Server Remote Code Execution Vulnerability KEVCVSS 3.1CRITICAL 9.8
See all 18045 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences