CVE-2026-73492
LowCVSS 2.3Exploitation Probability (EPSS)
Low risk16th percentile - higher than 16% of all known CVEs
Summary
Loofah from 2.25.0 until 2.25.2 does not reject javascript: or vbscript: URIs whose scheme is split by semicolon-less numeric character references such as :, 	, 
, or 
. CGI.unescapeHTML leaves these references encoded, so allowed_uri? reports the URL safe even though a browser decodes an encoded colon or strips encoded whitespace and executes the resulting URI scheme. 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.
Risk Assessment
An attacker could exploit this vulnerability to inject malicious JavaScript or VBScript, potentially leading to XSS attacks or data theft if the application uses allowed_uri? with unprocessed data.
Recommendation
Update Loofah to version 2.25.2 or later and avoid passing encoded strings directly to allowed_uri?.
Other vulnerabilities in Loofah
See all- GHSA-5qhf-9phg-95m2Low
Loofah::HTML5::Scrub.allowed_uri? does not correctly reject javascript: or vbscript: URIs when the scheme is split by a numeric character reference that has no trailing semicolon. A browser decodes such references and resolves the URL to an executable javascript: scheme, while allowed_uri? considers it safe.
- GHSA-9wjq-cp2p-hrgfMedium
Loofah's HTML5 sanitizer restricted only the xlink:href attribute on certain SVG elements to local, same-document references. Browsers also accept a plain href attribute as an alternative to the deprecated xlink:href per the SVG 2 spec, but Loofah did not apply the same restriction to it.
- GHSA-8whx-365g-h9vvLow
Loofah::HTML5::Scrub.allowed_uri? does not correctly reject javascript: URIs when the scheme is split or prefixed by the HTML5 named character references 	 (tab) or 
 (line feed). This is a bypass of the fix for GHSA-46fp-8f5p-pf2m, which handled the equivalent numeric character references.
- CVE-2026-73491Low
Loofah from 2.25.0 until 2.25.2 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.
- CVE-2026-73490Medium
Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. Prior to 2.25.2, Loofah's HTML5 sanitizer applies its local-reference restriction only to the xlink:href attribute on SVG use and feImage elements, while browsers also accept the plain href attribute. A crafted sanitized SVG can therefore reference an arbitrary same-origin external document; use may render external SVG content containing scripts or other dangerous content, and feImage may load external images for tracking. Applications that sanitize user-supplied SVG with Loofah's default allowlist are affected. This issue is fixed in version 2.25.2.
Original NVD description (English source)
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: or vbscript: URIs whose scheme is split by semicolon-less numeric character references such as :, 	, 
, or 
. CGI.unescapeHTML leaves these references encoded, so allowed_uri? reports the URL safe even though a browser decodes an encoded colon or strips encoded whitespace and executes the resulting URI scheme. 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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS