Vulnerability 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.
CVSS Score
CRITICAL
Related Weaknesses (CWE)
References
- https://github.com/microsoft/prompty/commit/e4a0ebf49e3a78d5d7796c8480bf9a4f0c54
- https://github.com/microsoft/prompty/commit/f5c57c94a0990cca79d095c3daab661b4b1f
- 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
FAQ
What is CVE-2026-73299?
CVE-2026-73299 is a vulnerability with a CVSS score of 10.0 (CRITICAL). 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 JavaScrip...
How severe is CVE-2026-73299?
CVE-2026-73299 has been rated CRITICAL with a CVSS base score of 10.0/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-73299?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.