A NULL pointer dereference vulnerability in QNAP’s QTS and QuTS hero operating systems allows remote attackers to trigger a denial‑of‑service condition. The flaw exploits improper null pointer handling (CWE‑476), causing the targeted device to become unresponsive to legitimate traffic after the exploitation occurs. The impact is system‑wide availability loss for the affected device.

The vulnerability affects QNAP Systems Inc. QTS and QuTS hero releases that precede the vendor‑issued fixed builds. Versions of QTS earlier than 5.2.9.3410 build 20260214, and QuTS hero releases before h5.2.9.3410 build 20260214, h5.3.4.3500 build 20260520, or h6.0.0.3397 build 20260206 are vulnerable.

The CVSS score for this flaw is 6.9, and the EPSS score is not reported, indicating limited public exploitation data. It is not listed in the CISA KEV catalog. The description states remote attackers can exploit the vulnerability, implying that the attack vector is remote but the exact network exposure is not detailed; it is inferred that the device must be reachable from an attacker network to launch the DoS.