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The vulnerability CVE-2025-52856 is an improper authentication (CWE-287) flaw in the QVR firmware for legacy QNAP VioStor Network Video Recorders (NVRs). It allows a remote, unauthenticated attacker to completely bypass the system’s authentication controls. The core technical failure is that the affected software does not properly validate a user’s claimed identity before granting access to protected functions or data. With a CVSS 4.0 vector of AV:N/AC:L/AT:N/PR:N/UI:N, the exploit requires no privileges (PR:N), no user interaction (UI:N), and has low attack complexity (AC:L), making it straightforward to launch over a network (AV:N). By crafting and sending specific requests to the vulnerable device’s management interface, an attacker can evade login checks and gain unauthorized administrative access. Successful exploitation leads to a full compromise of the system’s confidentiality, integrity, and availability (VC:H/VI:H/VA:H), enabling the attacker to access live and recorded surveillance footage, manipulate system configuration, delete data, or use the device as a foothold for lateral movement within the network.
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Platform: QNAP VioStor NVR
Version: QVR 5.1.x
Vulnerability : Improper Authentication
Severity: Critical
date: 2025-08-29
Prediction: 2025-06-21
What Undercode Say:
` Check current firmware version on QNAP device`
`getcfg system version`
` Curl command to test for unauthenticated endpoint access (Illustrative)`
`curl -vk http://
` Nmap script to identify QNAP devices on network`
`nmap -sV –script=http- -p80,8080,443 `
` Command to download patched firmware from QNAP`
`wget -O firmware.img “https://www.qnap.com/go/download”`
How Exploit:
An attacker sends a crafted HTTP request to a vulnerable management endpoint on the VioStor NVR. The request exploits a logic flaw in the authentication routine, tricking the system into believing the user is already logged in with valid credentials. This bypasses the login page entirely, granting the attacker a valid administrative session or direct access to protected API functions without needing a password. The attacker can then interact with the system as a fully authenticated administrator.
Protection from this CVE
Immediately update the QVR firmware to version 5.1.6 build 20250621 or later. If immediate patching is impossible, implement strict network segmentation: place the VioStor NVR on an isolated VLAN, block all inbound internet traffic to its management interface with a firewall, and restrict access to only trusted administrative IP addresses. Do not expose the device’s web management portal to the public internet.
Impact:
Complete system compromise. Unauthorized access, manipulation, or deletion of sensitive surveillance video footage and system data. Loss of confidentiality and integrity for all monitored locations. Potential for attackers to disrupt physical security operations and use the device to pivot into other corporate network segments.
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Sources:
Reported By: nvd.nist.gov
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