Prompty: Arbitrary code execution via JavaScript frontmatter in TypeScript loader

Summary The TypeScript Prompty loader used gray-matter without overriding executable frontmatter engines. gray-matter supports JavaScript frontmatter blocks such as ---js and evaluates them while parsing. An attacker-controlled .prompty file could therefore execute arbitrary JavaScript during...

CVE-2026-53597 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...