CVE-2026-33937

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.

• github.comhttps://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2
• github.comhttps://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9
• github.comhttps://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-2w6w-674q-4c4q
• access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:10175
• access.redhat.comhttps://access.redhat.com/errata/RHSA-2026:34342
• access.redhat.comhttps://access.redhat.com/security/cve/CVE-2026-33937
• bugzilla.redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=2452523
• security.access.redhat.comhttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33937.json