Firefox SmartWindow CVE-2026-20253 Private URL Exfiltration via Token Expansion

Ibrahim Saud@tektrix

•updated Jun 29, 2026•0•0•5

Detects potential exploitation of Firefox SmartWindow (CVE-2026-20253) involving token exfiltration via specific URL patterns, unauthorized configuration preference tampering (e.g., smartwindow.enabled, smartwindow.apiKey), or modifications to browser configuration files (prefs.js, user.js) by the Firefox process.