Cross-site scripting in Loofah - #VU159825
Published: November 6, 2026
Vulnerability identifier: #VU159825
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N]
CVE-ID: N/A
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows an unauthenticated remote attacker to execute script in a victim's browser through cross-site scripting.
The vulnerability exists due to incomplete HTML entity decoding in Loofah's public allowed_uri? string-level helper, which misclassifies HTML-encoded data URIs as safe plain text. An unauthenticated remote attacker can submit a data:text/html URL to applications that validate encoded strings with this helper and render approved URLs into browser-interpreted attributes, triggering script execution when a victim follows the URL.
Affected software
Loofah
Remediation
Install security update from vendor's website.
Loofah - update to 2.25.3