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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-33916 Detail

Description

Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, `resolvePartial()` in the Handlebars runtime resolves partial names via a plain property lookup on `options.partials` without guarding against prototype-chain traversal. When `Object.prototype` has been polluted with a string value whose key matches a partial reference in a template, the polluted string is used as the partial body and rendered without HTML escaping, resulting in reflected or stored XSS. Version 4.7.9 fixes the issue. Some workarounds are available. Apply `Object.freeze(Object.prototype)` early in application startup to prevent prototype pollution. Note: this may break other libraries, and/or use the Handlebars runtime-only build (`handlebars/runtime`), which does not compile templates and reduces the attack surface.


Metrics

 
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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2 GitHub, Inc. Patch 
https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9 GitHub, Inc. Release Notes 
https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-2qvq-rjwj-gvw9 GitHub, Inc. Exploit  Vendor Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') GitHub, Inc.  
CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') GitHub, Inc.  

Known Affected Software Configurations Switch to CPE 2.2

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Change History

2 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-33916
NVD Published Date:
03/27/2026
NVD Last Modified:
03/31/2026
Source:
GitHub, Inc.