Auth bypass in QNAP Qvr
CVE-2025-52856
An improper authentication vulnerability has been reported to affect VioStor. If a remote attacker, they can then exploit the vulnerability to compromise the security of the system. We have already fixed the vulnerability in the following version: VioStor 5.1.6 build 20250621 and later
Vulnerability class: Broken Authentication
Published · last modified .
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: 0.006 (48.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 48.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000
Affected products
- QNAP Qvr — versions 5.1.6
- QNAP Systems Inc. Viostor — versions 5.1.0
Weakness classification (CWE)
References
- www.qnap.com/en/security-advisory/qsa-25-29 (Vendor Advisory)
Frequently asked questions
- What is CVE-2025-52856?
- CVE-2025-52856 is a critical-severity vulnerability in QNAP Qvr, classified under Improper Authentication. CVSS score: 9.8/10. Published 2025-08-29.
- How severe is CVE-2025-52856?
- Critical severity. CVSS v3 base score is 9.8 out of 10.