CVE-2026-33937

Fixed in a distro release EPSS 2%CVSS 9.8

Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, `Handlebars.compile()` accepts a pre-parsed AST object in addition to a template string. The `value` field of a `NumberLiteral` AST node is emitted directly into the generated JavaScript without quoting or sanitization. An attacker who can supply a crafted AST to `compile()` can therefore inject and execute arbitrary JavaScript, leading to Remote Code Execution on the server. Version 4.7.9 fixes the issue. Some workarounds are available. Validate input type before calling `Handlebars.compile()`; ensure the argument is always a `string`, never a plain object or JSON-deserialized value. Use the Handlebars runtime-only build (`handlebars/runtime`) on the server if templates are pre-compiled at build time; `compile()` will be unavailable.

Published 2026-03-27 · CVE record · OSV

Products: handlebars-lang handlebars.js, Red Hat Cluster Observability Operator 1.5.0, Red Hat OpenShift Dev Spaces 3.27, Red Hat Cryostat 4, Logging Subsystem for Red Hat OpenShift, Red Hat Data Grid 8, Red Hat Developer Hub, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift AI (RHOAI), Red Hat OpenShift Dev Spaces, Red Hat Process Automation 7

Fixed upstream

Distro releases