CVE-2026-33937
Handlebars.js has JavaScript Injection via AST Type Confusion
At a glance
- Source
- NVD
- EPSS
- EPSS 1.91 % · percentile 80 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Modified
Description
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.
Weaknesses (CWE)
- CWE-843 — Access of Resource Using Incompatible Type
- CWE-94 — Improper Control of Generation of Code
References
- https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-2w6w-674q-4c4q
- https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2
- https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9
- 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
- https://access.redhat.com/errata/RHSA-2026:34342
- https://access.redhat.com/errata/RHSA-2026:10175
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | CRITICAL 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | GitHub_M |
| CVSS 3.1 | CRITICAL 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | redhat-SADP |
| CVSS 3.1 | CRITICAL 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | CRITICAL 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | NVD · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Secondary) |
Advisories
- GHSA-2w6w-674q-4c4q — Handlebars.js has JavaScript Injection via AST Type Confusion
European references
- ENISA EUVD · EUVD-2026-16848
- GCVE · GCVE-0-2026-33937
CERT-FR advisories
- CERTFR-2026-AVI-1032 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0667 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0581 — Multiples vulnérabilités dans MongoDB · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:a:handlebarsjs:handlebars:*:*:*:*:*:node.js:*:*≥ 4.0.0 < 4.7.9
Affected products
| Product | Versions |
|---|---|
| handlebars-lang · handlebars.js | affected >= 4.0.0, < 4.7.9 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |