Uncaught Exception Affecting hbs package, versions >=4.3.0 <4.3.1
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-JS-HBS-19784397
- published14 Sept 2026
- disclosed11 Sept 2026
- creditAlfredo González
Introduced: 11 Sep 2026
NewCVE-2026-87123 (opens in a new tab)How to fix?
Upgrade hbs to version 4.3.1 or higher.
Overview
hbs is an Express.js template engine plugin for Handlebars
Affected versions of this package are vulnerable to Uncaught Exception in its async helper output escaping, where a helper value carrying a truthy but non-callable toHTML property causes handlebars' escapeExpression to invoke it as a method and throw a TypeError. An attacker can crash the Node.js process by supplying a value such as {"toHTML":"x"} that reaches an async helper, since the TypeError is thrown asynchronously outside the render function's try-catch and no Express error handler can intercept it. This affects only 4.3.0 and requires the application to register helpers with registerAsyncHelper and pass externally influenced or parsed values into them.