CVE-2026-53597CWE-94

Prompty: Arbitrary code execution via JavaScript frontmatter in TypeScript loader

High · published July 16, 2026

CVSS v4.0
8.7
EPSS
1%
Percentile
61.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
8.7 · HIGH
Vector
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
EPSS
0.00972 · 61.6th percentile
Weakness
CWE-94 · Improper Control of Generation of Code ('Code Injection')
Published
2026-07-16T14:54Z
EPSS history
Timeline
  • 16 JUL 14:54Z
    Prompty: Arbitrary code execution via JavaScript frontmatter in TypeScript loader
    cvelistv5