Bug 2514986 (CVE-2026-73491)

Summary:	CVE-2026-73491 rubygem-loofah: Loofah: Cross-Site Scripting via malformed `javascript:` URI parsing
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	akostadi, amasferr, anthomas, dmayorov, ehelms, eshamard, ggainey, jlledo, jpasqual, juwatts, jvasik, kaycoth, mdellweg, mhulan, nmoumoul, osousa, pantinor, pcreech, rblanco, rchan, smallamp, tmalecek, tsedmik
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in Loofah. The `Loofah::HTML5::Scrub.allowed_uri?` function fails to properly detect `javascript:` Uniform Resource Identifiers (URIs) when their scheme is split or prefixed with HTML5 named whitespace character references, such as `&Tab;` or `&NewLine;`. This vulnerability allows a remote attacker to craft a malicious URI that, when processed by affected callers, is incorrectly deemed safe. Consequently, a web browser will decode and execute the embedded JavaScript code, leading to Cross-Site Scripting (XSS) and potential arbitrary code execution in the user's browser context.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-08-12 21:01:26 UTC

Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. From 2.25.0 until 2.25.2, Loofah::HTML5::Scrub.allowed_uri? does not reject javascript: URIs whose scheme is split or prefixed with the HTML5 named whitespace character references &Tab; or &NewLine;. CGI.unescapeHTML leaves those references intact, so allowed_uri? reports the URL safe even though a browser decodes and strips the tab or line feed and executes the resulting javascript: URL. This issue affects only callers that pass HTML-encoded strings directly to allowed_uri?; Loofah's default sanitize() path is not affected. This issue is fixed in version 2.25.2.