CVE-2026-33937
critical · 9.8Handlebars 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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weaknesses
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| handlebarsjs | handlebars | >= 4.0.0, < 4.7.9 |
Check a specific version with /api/v1/cve/match.
References
- https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2
- https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9
- https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-2w6w-674q-4c4q
- https://access.redhat.com/errata/RHSA-2026:10175
- https://access.redhat.com/errata/RHSA-2026:34342
- https://access.redhat.com/security/cve/CVE-2026-33937
- https://bugzilla.redhat.com/show_bug.cgi?id=2452523
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33937.json
Query this programmatically:
curl https://evil-db.io/api/v1/cve/CVE-2026-33937