CVE-2026-54221: Ubb Systems Ubb.threads

Medium severity, CVSS 5.1. EPSS: 0.5% chance of exploitation in the next 30 days.

UBB.threads is vulnerable to Reflected XSS. The application improperly handles user input in certain requests, enabling attackers to execute arbitrary JavaScript in the context of a victim's browser by tricking them into clicking a crafted link.  Because vendor contact attempts were unsuccessful, the vulnerability has only been confirmed in version 7.7.5 but may also affect other versions.

Affected products

• Ubb Systems Ubb.threads: up to and including 7.7.5

Published 2026-06-18. Last modified 2026-06-18.