GHSA-w28w-gp39-m4p6: Prompty: Server-Side Template Injection to Remote Code Execution in the @prompty/core Nunjucks Renderer

July 24, 2026

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.

References

github.com/advisories/GHSA-w28w-gp39-m4p6
github.com/microsoft/prompty/commit/047756f4c8caf91c5868eeb42520c938393277b0
github.com/microsoft/prompty/pull/404
github.com/microsoft/prompty/security/advisories/GHSA-w28w-gp39-m4p6

Code Behaviors & Features

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