CVE-2021-34343: QNAP QTS

High severity, CVSS 7.2. EPSS: 2% chance of exploitation in the next 30 days.

A stack buffer overflow vulnerability has been reported to affect QNAP device running QTS, QuTScloud, QuTS hero. If exploited, this vulnerability allows attackers to execute arbitrary code. We have already fixed this vulnerability in the following versions of QTS, QuTScloud, QuTS hero: QTS 4.5.4.1715 build 20210630 and later QTS 5.0.0.1716 build 20210701 and later QuTScloud c4.5.6.1755 and later QuTS hero h4.5.4.1771 build 20210825 and later

Affected products

• QNAP QTS: before 4.3.3.1693 (fixed in 4.3.3.1693); from 4.3.4, before 4.3.6.1750 (fixed in 4.3.6.1750); from 4.4.0, before 4.5.4.1715 (fixed in 4.5.4.1715); from 5.0.0, before 5.0.0.1716 (fixed in 5.0.0.1716)
• QNAP Quts Hero: before h4.5.4.1771 (fixed in h4.5.4.1771)
• QNAP Qutscloud: before c4.5.6.1755 (fixed in c4.5.6.1755)

Published 2021-09-10. Last modified 2026-06-17.