CVE-2025-52856Network attack vector

Unauthenticated system compromise

Published Aug 29, 2025 · Updated Feb 26, 2026

Improper authentication in QNAP VioStor NVR 5.1.0 through versions before 5.1.6 build 20250621 allows remote attackers to compromise the system. QNAP has not disclosed the affected endpoint or the incorrect authentication operation performed on network requests. No credentials or user interaction are required, but the available material does not specify which data-access, modification, or service-interruption actions the compromise enables.

CVSS severity9.3
Critical
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in QNAP VioStor NVR 5.1.0 through versions before 5.1.6 build 20250621 allows remote attackers to compromise the system. QNAP has not disclosed the affected endpoint or the incorrect authentication operation performed on network requests. No credentials or user interaction are required, but the available material does not specify which data-access, modification, or service-interruption actions the compromise enables.

The record

CVE
CVE-2025-52856
Published
Aug 29, 2025
Updated
Feb 26, 2026
Vendor
Linn Products Limited
Product
VioStor NVR
Classifications
CWE-287, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 29, 2025CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.1.0 <5.1.6 build 20250621

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Linn Products Limited · VioStor NVRversion=5.1.0 <5.1.6 build 20250621

Published CVSS scores

9.3QNAP Systems, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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