CVE-2019-20920: Handlebarsjs Handlebars

High severity, CVSS 8.1. EPSS: 3.2% chance of exploitation in the next 30 days.

Handlebars before 3.0.8 and 4.x before 4.5.3 is vulnerable to Arbitrary Code Execution. The lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript. This can be used to run arbitrary code on a server processing Handlebars templates or in a victim's browser (effectively serving as XSS).

Affected products

• Handlebarsjs Handlebars: before 3.0.8 (fixed in 3.0.8); from 4.0.0, before 4.5.3 (fixed in 4.5.3)

Published 2020-09-30. Last modified 2026-10-08.