Incomplete List of Disallowed Inputs Affecting org.webjars.npm:handlebars package, versions [4.7.2,]
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JAVA-ORGWEBJARSNPM-20557396
- published7 Oct 2026
- disclosed6 Oct 2026
- creditBrandon T. Elliott
Introduced: 6 Oct 2026
NewCVE-2026-106445 (opens in a new tab)How to fix?
A fix was pushed into the master branch but not yet published.
Overview
org.webjars.npm:handlebars is an extension to the Mustache templating language.
Affected versions of this package are vulnerable to Incomplete List of Disallowed Inputs in the lookupProperty function in lib/handlebars/runtime.js, which returns the resolved value as soon as Object.prototype.hasOwnProperty.call(parent, propertyName) holds, without consulting the prototype access deny list, and constructor is an own property of every prototype object, so Function.prototype.constructor resolves to Function itself. An attacker can execute code on the server by rendering a template that walks to a prototype and reads its constructor, as in {{lookup (lookup fn "__proto__") "constructor"}}. This requires the attacker to control the template rather than only the data, and compilation with allowProtoMethodsByDefault: true.
Workaround
This vulnerability can be avoided by leaving allowProtoMethodsByDefault at its default of false when compiling untrusted templates.