Bug 2548550

Summary: CVE-2026-106445 boost: Handlebars: JavaScript Injection via Own Property Check Bypass [fedora-all]
Product: [Fedora] Fedora Reporter: Srikanth Balasubramanian <sbalasub>
Component: boostAssignee: Jonathan Wakely <jwakely>
Status: CLOSED NOTABUG QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: high    
Version: rawhideCC: denis.arnaud_fedora, jwakely, laurent.rineau__fedora, mcermak, ppalka
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["b8c9c1fb-fc31-4bd9-a7d7-af85309b86ef"]}
Fixed In Version: Doc Type: ---
Doc Text:
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Clone Of: Environment:
Last Closed: 2026-10-09 13:14:32 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 2547112    

Description Srikanth Balasubramanian 2026-10-09 12:28:39 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

Handlebars provides the power necessary to let users build semantic templates. From 4.0.0 until 4.7.10, Handlebars lookupProperty returns Function.prototype.constructor before applying the prototype-access deny list because constructor is an own property of Function.prototype. When an attacker can render a controlled template with allowProtoMethodsByDefault enabled and an accessible function in the template context, the template can traverse from that function through its prototype to Function.prototype and then obtain the Function constructor through the own-property bypass. This permits attacker-controlled JavaScript to execute with the server application's privileges. This issue is fixed in version 4.7.10.
Comment 1 Jonathan Wakely 2026-10-09 13:14:32 UTC 
As I have said repeatedly:

The CVE does not affect Boost. The Node modules are only used to generate HTML files during preparation of the release tarball, and are not used during the RPM build and are not part of the installed RPMs.

I checked this with upstream and was told "The npm packages are only required at doc build time, so it makes
sense to not include them in the release tarball."
https://lists.boost.org/archives/list/boost@lists.boost.org/thread/APKJIASXU2DLQMGYIQR4JOMJE5CB56KB/

The Boost 1.92.0 release will not include those files in the release tarball at all, due to https://github.com/boostorg/release-tools/pull/111 which was already changed in March. That PR says "Remove "doc/node_modules" from libraries after the build. Since that directory adds extra MBs, and isn't needed."