CVE-2026-53597

HIGH

Prompty: Arbitrary code execution via JavaScript frontmatter in TypeScript loader

Title source: cna
STIX 2.1

Description

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.

References (2)

Core 2

Scores

CVSS v4 8.7
EPSS 0.0093
EPSS Percentile 57.1%
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-94
Status published
Products (2)
microsoft/prompty >= 2.0.0-alpha.1, < 2.0.0-beta.3
prompty/core 2.0.0-alpha.1 - 2.0.0-beta.3npm
Published Jul 16, 2026
Tracked Since Jul 16, 2026