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

• npm @prompty/core: < 0.1.5 → fixed in 0.1.5 • npm @prompty/core: >= 2.0.0-alpha.1, < 2.0.0-beta.5 → fixed in 2.0.0-beta.5

Summary 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. Affected packages • npm `@prompty/core` versions `<= 0.1.4` • npm `@prompty/core` versions `<= 2.0.0-beta.4` Impact Applications that render untrusted, community-supplied, cloned, or LLM-generated `.prompty` files with the TypeScript runtime could allow attacker-controlled code execution with the privileges of the Node.js host process. Remediation Upgrade to `@prompty/core` `2.0.0-beta.5` or later. The patched renderer sanitizes render inputs to own-data-only values, rejects constructor/prototype member traversal, and disallows template function calls. Ordinary interpolation, conditionals, loops, and own nested data properties remain supported. Fix details The fix is merged in PR #404 and includes regression coverage for default Nunjucks rendering, explicit renderer usage, unsafe member lookups, and attempted template function calls.