high8.7
CVE-2026-53597
Prompty: Arbitrary code execution via JavaScript frontmatter in TypeScript loader
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | @prompty/core | >= 2.0.0-alpha.1, < 2.0.0-beta.3 | 2.0.0-beta.3 |