Jul 2026: Prompty: Arbitrary code execution via JavaScript frontmatter in TypeScript loader
CVE-2026-53597 Published on July 16, 2026

Prompty: Arbitrary code execution via JavaScript frontmatter in TypeScript loader
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.

NVD

Weakness Type

What is a Code Injection Vulnerability?

The software constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

CVE-2026-53597 has been classified to as a Code Injection vulnerability or weakness.


Affected Versions

microsoft prompty Version >= 2.0.0-alpha.1, < 2.0.0-beta.3 is affected by CVE-2026-53597