Incomplete List of Disallowed Inputs in Loofah - CVE-2026-73491
Published: November 6, 2026
Vulnerability identifier: #VU159820
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-73491
CWE-ID: CWE-184
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows an unauthenticated remote attacker to execute JavaScript in a victim's browser through applications using Loofah.
The vulnerability exists due to incomplete handling of named whitespace character references in allowed_uri? when callers validate HTML-encoded URLs and render approved values into browser-interpreted URI attributes. An unauthenticated remote attacker can submit a javascript: URL split by 	 or 
 to bypass validation and execute script when a victim follows the rendered link.
Affected software
Loofah
How to mitigate CVE-2026-73491
Install security update from vendor's website.
Loofah - update to 2.25.2