What’s Vulnerable › Vulnerabilities

CVE-2026-73491: Loofah `allowed_uri?` does not detect `javascript:` URIs split by named whitespace character references

• Severity: low (CVSS 2.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-12 · updated 2026-10-24
• Weakness: CWE-184

Description

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 	 or 
. 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.

Affected products

• flavorjones loofah: from 2.25.0, < 2.25.2

References

• https://github.com/flavorjones/loofah/commit/5e91af861e3cdab47b91dd0b81f3afdfd13a5e19
• https://github.com/flavorjones/loofah/pull/308
• https://github.com/flavorjones/loofah/releases/tag/v2.25.2
• https://github.com/flavorjones/loofah/security/advisories/GHSA-8whx-365g-h9vv

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