RCE in Handlebars-lang Handlebars.js
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`…
EPSS: 0.002 (47.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Handlebars-lang Handlebars.js — versions >= 4.0.0, < 4.7.9
Weakness classification (CWE)
Public proof-of-concept exploits
References
- https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-2w6w-674q-4c4q (x_refsource_CONFIRM)
- https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2 (x_refsource_MISC)
- https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9 (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-33937?
- CVE-2026-33937 is a critical-severity vulnerability in Handlebars-lang Handlebars.js, classified under Access of Resource Using Incompatible Type (Type Confusion). CVSS score: 9.8/10. Published 2026-03-27.
- How severe is CVE-2026-33937?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2026-33937 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.