What is CVE-2025-66276?

CVE-2025-66276 is a critical-severity vulnerability in QNAP Qts. CVSS score: 9.8/10. Published 2026-06-10.

How severe is CVE-2025-66276?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Vulnerability in QNAP Qts

CVE-2025-66276

QuTS hero is not affected. We have already fixed the vulnerability in the following version: QTS 5.2.7.3256 build 20250913 and later

Published 2026-06-10 · last modified 2026-07-23.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.003 (19.4th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

References

www.qnap.com/en/security-advisory/qsa-25-56 (Vendor Advisory)

Frequently asked questions

What is CVE-2025-66276?: CVE-2025-66276 is a critical-severity vulnerability in QNAP Qts. CVSS score: 9.8/10. Published 2026-06-10.
How severe is CVE-2025-66276?: Critical severity. CVSS v3 base score is 9.8 out of 10.