Improper Handling of Case Sensitivity in Loofah - #VU159822
Published: November 6, 2026
Vulnerability identifier: #VU159822
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-178
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows an unauthenticated remote attacker to expose a viewer's IP address, user agent, and referrer through attacker-directed requests.
The vulnerability exists due to incomplete local-reference checks for SVG textPath and mpath elements in Loofah's default allowlist, also reused by rails-html-sanitizer when SVG is permitted. An unauthenticated remote attacker can submit SVG containing external references that survive sanitization and trigger requests to attacker-chosen URLs, including viewer-network hosts, when a victim views the content in Firefox.
Affected software
Loofah
Remediation
Install security update from vendor's website.
Loofah - update to 2.25.3