CVE-2026-73299
Medium
Elevated severity or exploit probability.
CVSS base
10.0
CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS — probability of exploitation (30 days)
1.8%
77.3th percentile
CISA KEV
Not listed
Weakness / dates
CWE-94
Published 2026-08-12 · modified 2026-09-09
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.
References
- 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