Bug 2452523 (CVE-2026-33937)

Summary: CVE-2026-33937 handlebars.js: Handlebars: Remote Code Execution via crafted Abstract Syntax Tree object in compile()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: aazores, abuckta, cmah, dhanak, dkuc, drosa, eaguilar, ebaron, gotiwari, ibek, jcantril, jgrulich, jhorak, jkoehler, jolong, jrokos, lchilton, lphiri, mnovotny, mvyas, orabin, pjindal, rhel-process-autobot, rojacob, sausingh, sdawley, sfeifer, tpopela, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in Handlebars. An attacker can exploit this by supplying a crafted Abstract Syntax Tree (AST) object to the `Handlebars.compile()` function. This allows the injection and execution of arbitrary JavaScript code due to improper sanitization of the `value` field in `NumberLiteral` AST nodes. This vulnerability can lead to Remote Code Execution (RCE) on the server.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 2452595, 2452598, 2452606, 2452612, 2452640, 2452588, 2452589, 2452591, 2452615, 2452618, 2452622, 2452628, 2452632, 2452638, 2452643    
Bug Blocks:    

Description OSIDB Bzimport 2026-03-27 22:03:14 UTC 
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.