CVE-2025-66281: QTS, QuTS hero

Severity: high (CVSS 7.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-10 · updated 2026-07-23
Weakness: CWE-476

Description

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 Systems Inc. QuTS hero: from h5.2.0.2737 before h5.2.9.3410; from h5.3.0.3115 before h5.3.4.3500; from h6.0.0.3324 before h6.0.0.3397 — fixed in h5.2.9.3410, h5.3.4.3500, h6.0.0.3397

How to fix

Upgrade to a fixed version: QNAP QTS 5.2.9.3410; QNAP Systems Inc. QuTS hero h5.2.9.3410, h5.3.4.3500, h6.0.0.3397. Check the vendor advisory for mitigations.

References

https://www.qnap.com/en/security-advisory/qsa-26-10

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