CVE-2026-33937Handlebars provides the power necessary to let users build semantic templates.
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 9.8 CRITICAL (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-94, CWE-843
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Modified
- Record last updated
- Sep 4, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
handlebarsjs handlebars handlebarsjs:handlebars | from 4.0.0 before 4.7.9 | NVD |
References
- https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2patch
- https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9release-notes
- https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-2w6w-674q-4c4qexploit, vendor-advisory
- 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
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.