CVE-2021-28806: QNAP QTS

Medium severity, CVSS 5.4. EPSS: 0.5% chance of exploitation in the next 30 days.

A DOM-based XSS vulnerability has been reported to affect QNAP NAS running QTS and QuTS hero. If exploited, this vulnerability allows attackers to inject malicious code. This issue affects: QNAP Systems Inc. QTS versions prior to 4.5.3.1652 Build 20210428. QNAP Systems Inc. QuTS hero versions prior to h4.5.2.1638 Build 20210414. QNAP Systems Inc. QuTScloud versions prior to c4.5.5.1656 Build 20210503. This issue does not affect: QNAP Systems Inc. QTS 4.3.6; 4.3.3.

Affected products

• QNAP QTS: before 4.5.3.1652 (fixed in 4.5.3.1652)
• QNAP Quts Hero: before h4.5.2.1638 (fixed in h4.5.2.1638)
• QNAP Qutscloud: before c4.5.5.1656 (fixed in c4.5.5.1656)

Published 2021-06-03. Last modified 2026-06-17.