Main Vulnerability Database Vulnerabilities #VU124842

Code Injection in handlebars.js - CVE-2026-33937

Published: April 2, 2026 / Updated: April 30, 2026

Vulnerability identifier: #VU124842

CSH Severity: High

CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-33937

CWE-ID: CWE-94

Exploitation vector: Remote access

Exploit availability: Public exploit is available

Vulnerability details

The vulnerability allows a remote attacker to execute arbitrary code.

The vulnerability exists due to improper control of code generation in Handlebars.compile() and the JavaScript code generator when processing a crafted pre-parsed AST object. A remote attacker can supply a crafted AST with a malicious NumberLiteral value to execute arbitrary code.

The issue affects cases where user-controlled JSON or other untrusted input is deserialized and passed directly to compile() as an AST object instead of a template string, and no user interaction is required.

Affected software

handlebars.js
Storage Defender Copy Data Management
Fedora
IBM App Connect Enterprise
nextcloud

How to mitigate CVE-2026-33937

Install security update from vendor's website.

handlebars.js - update to 4.7.9
Storage Defender Copy Data Management - update to 2.3.1.0
IBM App Connect Enterprise - addressed in versions 12.0.12.25, 13.0.7.1
nextcloud - addressed in versions 33.0.3-1.el10_2, 33.0.3-1.el10_3, 33.0.3-1.fc42, 33.0.3-1.fc43, 33.0.3-1.fc44

Links to Public Exploits and PoC-codes

Exploit #12683 - cve-2026-33937 (CVE-2026-33937 Handlebars RCE exploit PoC (AST Injection)) (April 30, 2026)

External References

https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-2w6w-674q-4c4q