Description
Handlebars can expose the Function constructor despite its prototype-access deny list. When a template reaches Function.prototype, its own constructor property is returned before the deny list is checked.
Recommendation
Update the handlebars package to the latest compatible version. Followings are version details:
- Affected version(s): >= 3.0.0, <= 4.7.9
- Patched version(s): 4.7.10
References
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Start a free scanRelated Issues
- Handlebars: JavaScript Injection via AST Type Confusion in compile (bypass of CVE-2026-33937) - CVE-2026-106446
- Handlebars.js has JavaScript Injection via AST Type Confusion by tampering @partial-block - CVE-2026-33938
- Handlebars.js has JavaScript Injection via AST Type Confusion - CVE-2026-33937
- Unhead has XSS bypass in `useHeadSafe` via attribute name injection and case-sensitive protocol check - CVE-2026-31860
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See something that needs correcting? Let us knowUpdated October 12, 2026