CVE-2025-66281: QNAP QTS

High severity, CVSS 7.2. EPSS: 0.5% chance of exploitation in the next 30 days.

A NULL pointer dereference vulnerability has been reported to affect several QNAP operating system versions. The remote attackers can then exploit the vulnerability to launch a denial-of-service (DoS) attack. We have already fixed the vulnerability in the following versions: QTS 5.2.9.3410 build 20260214 and later QuTS hero h5.2.9.3410 build 20260214 and later QuTS hero h5.3.4.3500 build 20260520 and later QuTS hero h6.0.0.3397 build 20260206 and later

Affected products

• QNAP QTS: from 5.2.0.2737, before 5.2.9.3410 (fixed in 5.2.9.3410)
• QNAP Quts Hero: from h5.2.0.2737, before h5.2.9.3410 (fixed in h5.2.9.3410); from h5.3.0.3115, before h5.3.4.3500 (fixed in h5.3.4.3500); from h6.0.0.3324, before h6.0.0.3397 (fixed in h6.0.0.3397)

Published 2026-06-10. Last modified 2026-07-23.