CVE-2021-28800: QNAP QTS

Critical severity, CVSS 9.8. EPSS: 1.4% chance of exploitation in the next 30 days.

A command injection vulnerability has been reported to affect QNAP NAS running legacy versions of QTS. If exploited, this vulnerability allows attackers to execute arbitrary commands in a compromised application. This issue affects: QNAP Systems Inc. QTS versions prior to 4.3.6.1663 Build 20210504; versions prior to 4.3.3.1624 Build 20210416. This issue does not affect: QNAP Systems Inc. QTS 4.5.3. QNAP Systems Inc. QuTS hero h4.5.3. QNAP Systems Inc. QuTScloud c4.5.5.

Affected products

• QNAP QTS: before 4.3.3.1624 (fixed in 4.3.3.1624); from 4.3.4, before 4.3.6.1663 (fixed in 4.3.6.1663)

Published 2021-06-24. Last modified 2026-06-17.