RCE in Microsoft Prompty
CVE-2026-53597
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.
Vulnerability class: RCE (Remote Code Execution)
Published · last modified .
EPSS exploit prediction
EPSS: 0.010 (61.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 62nd percentile — 61.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: 0.000
Affected products
- Microsoft Prompty — versions >= 2.0.0-alpha.1, < 2.0.0-beta.3