CVE-2026-73299

CRITICAL

CVE: CVE-2026-73299 - Prompty is a markdown file format (Sign in to save

CVSS

10.0

CVSS v3.1

EPSS

N/A

Exploit Prediction Score

Published

August 12, 2026

Exploitability

No EPSS data available

Description

Prompty is a markdown file format (.prompty) for LLM prompts. Prior to 0.1.5 and 2.0.0-beta.5, the TypeScript Nunjucks renderer evaluated untrusted .prompty template bodies with unrestricted JavaScript member access. An attacker-controlled template could traverse constructor and prototype properties to execute JavaScript in the host Node.js process. This issue is fixed in versions 0.1.5 and 2.0.0-beta.5.

Weaknesses

CWE-94CWE-1336

Affected Packages

No package data available.

Aliases

CVE-2026-73299

Related references

Publisher and database URLs for this record (shown for attribution; reading stays in Bugflare).

https://github.com/microsoft/prompty/commit/e4a0ebf49e3a78d5d7796c8480bf9a4f0c54d19e
https://github.com/microsoft/prompty/commit/f5c57c94a0990cca79d095c3daab661b4b1fb89f
https://github.com/microsoft/prompty/pull/404
https://github.com/microsoft/prompty/pull/405
https://github.com/microsoft/prompty/security/advisories/GHSA-w28w-gp39-m4p6
https://github.com/microsoft/prompty/tree/typescript/2.0.0-beta.5