Bug 2547120 (CVE-2026-106446)

Summary:	CVE-2026-106446 handlebars: Handlebars: JavaScript Injection via AST Type Confusion in compile (Program.blockParams)
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	aazores, abarbaro, abrianik, abuckta, alizardo, ataylor, bbrownin, cmah, csuconic, dbosanac, dbruscin, dkuc, doconnor, dschmidt, eaguilar, ebaron, ehugonne, fmariani, gbenhaim, ggrzybek, gmalinko, gotiwari, gparvin, gtully, ikhan, janstey, jbalunas, jchui, jhe, jhorak, jlanda, jmatsuok, jraez, jreimann, jsherman, jtolenti, jwon, kshier, ktsao, kvanderr, lchilton, mcarlett, mdessi, mrizzi, mvyas, nboldt, niyer, oaljalju, orabin, parichar, pcattana, pjindal, psrna, rbobbitt, rgemmell, rgodfrey, rhaigner, rhel-process-autobot, rstepani, sdawley, sfeifer, simaishi, stcannon, tasato, tbish, tcunning, tlavocat, tsze, twaugh, watson-tool-maintainers, yfang, yguenane
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in Handlebars. Incomplete validation of pre-parsed AST objects passed to compile() or precompile() allows unchecked AST fields to be emitted into generated JavaScript. An attacker who can supply an object instead of a template string can inject and execute arbitrary JavaScript in the application process.	Story Points:	---
Clone Of:		Environment:
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Regression:	---	Mount Type:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2548549, 2548556, 2548557, 2548558, 2548561, 2548551, 2548553, 2548555, 2548559, 2548560
Bug Blocks:

Description OSIDB Bzimport 2026-10-06 19:55:12 UTC

Handlebars provides the power necessary to let users build semantic templates. From 4.0.0 until 4.7.10, Handlebars.compile() and Handlebars.precompile() accept pre-parsed AST objects while validating only selected PathExpression, NumberLiteral, and BooleanLiteral values. This issue bypasses the AST validation introduced in version 4.7.9 for CVE-2026-33937. An attacker who can supply an object instead of a template string can place JavaScript expressions in unchecked values such as Program.blockParams.length, a non-PathExpression parameter depth, a non-string StringLiteral.value, or a non-string PathExpression.original. The compiler emits those values into generated JavaScript, causing code execution in the server process when compile output renders or wherever precompile output is loaded. Applications that pass only template strings are not affected. This issue is fixed in version 4.7.10.