Vulnerability library
Security checkMarch 29, 2026

Handlebars.js has a Prototype Method Access Control Gap via Missing __lookupSetter__ Blocklist Entry

Understand the exposure, see the recommended fix, and check whether your own website has related weaknesses.

Medium severitynpmhandlebars

Check your website

Find this and other vulnerabilities with a free scan.

Your scan runs on your computer. No account required.

Description

The prototype method blocklist in lib/handlebars/internal/proto-access.js blocks constructor, __defineGetter__, __defineSetter__, and __lookupGetter__, but omits the symmetric __lookupSetter__.

Recommendation

Update the handlebars package to the latest compatible version. Followings are version details:

  • Affected version(s): >= 4.6.0, <= 4.7.8
  • Patched version(s): 4.7.9

References

Could your website be exposed too?

SmartScanner can check your website for Handlebars.js has a Prototype Method Access Control Gap via Missing __lookupSetter__ Blocklist Entry and gives you actionable findings to investigate.

Start a free scan

Related Issues

See something that needs correcting? Let us knowUpdated March 29, 2026