Access of Resource Using Incompatible Type ('Type Confusion') Affecting handlebars package, versions >=4.0.0 <4.7.9
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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Start learning- Snyk IDSNYK-JS-HANDLEBARS-15803086
- published29 Mar 2026
- disclosed27 Mar 2026
- creditevanj2357
Introduced: 27 Mar 2026
NewCVE-2026-33940 (opens in a new tab)How to fix?
Upgrade handlebars to version 4.7.9 or higher.
Overview
handlebars is an extension to the Mustache templating language.
Affected versions of this package are vulnerable to Access of Resource Using Incompatible Type ('Type Confusion') via the resolvePartial and invokePartial functions. An attacker can execute arbitrary code on the server by supplying a crafted object as a dynamic partial in the template context, which is then compiled and executed as JavaScript.
Note: This is only exploitable if the template uses dynamic partial lookups and the attacker can control the context property used for the lookup.
Workaround
This vulnerability can be mitigated by using the runtime-only build require('handlebars/runtime'), sanitizing context data to prevent non-primitive objects from being passed to dynamic partials, or avoiding dynamic partial lookups when context data is user-controlled.