CVE-2025-53595 is a high-severity SQL injection vulnerability affecting QNAP Systems Inc.'s Qsync Central product, specifically version 5.0.0. This vulnerability is classified under CWE-89, which pertains to improper neutralization of special elements used in an SQL command ('SQL Injection'). The flaw allows a remote attacker who has already obtained a user account on the affected system to exploit the vulnerability without requiring additional user interaction or elevated privileges beyond that user account. By leveraging this SQL injection, the attacker can execute unauthorized code or commands on the backend database, potentially leading to unauthorized data access, data manipulation, or even full system compromise depending on the database and application architecture. The vulnerability was addressed and fixed in Qsync Central version 5.0.0.2 released on July 31, 2025. The CVSS v4.0 base score is 8.6, indicating a high severity with network attack vector, low attack complexity, no user interaction, and privileges required at the user level. The impact on confidentiality and integrity is high, while availability impact is none. No known exploits are reported in the wild as of the publication date.

For European organizations using Qsync Central 5.0.0, this vulnerability poses a significant risk. Qsync Central is typically used for file synchronization and sharing, often in enterprise or SMB environments, meaning sensitive corporate data could be exposed or altered. Exploitation could lead to unauthorized data disclosure, data tampering, or lateral movement within the network if attackers escalate privileges after initial compromise. Given the network-based attack vector and lack of user interaction required, attackers could automate exploitation once a user account is compromised, increasing the risk of widespread impact. This could disrupt business operations, cause data breaches subject to GDPR penalties, and damage organizational reputation. The absence of known exploits in the wild currently reduces immediate risk, but the high CVSS score and ease of exploitation warrant urgent attention. Organizations relying on Qsync Central for critical file synchronization should prioritize patching to prevent potential exploitation.

European organizations should immediately upgrade Qsync Central to version 5.0.0.2 or later to remediate this vulnerability. Beyond patching, organizations should enforce strong user account security measures, including multi-factor authentication (MFA) to reduce the risk of account compromise, since exploitation requires a valid user account. Network segmentation should be applied to limit access to Qsync Central servers only to trusted internal networks or VPN users. Implementing web application firewalls (WAFs) with SQL injection detection and prevention rules can provide an additional layer of defense. Regularly audit user accounts and permissions to ensure least privilege principles are enforced. Monitoring and logging of database queries and application logs should be enhanced to detect suspicious activities indicative of SQL injection attempts. Finally, organizations should conduct penetration testing and vulnerability assessments on their Qsync Central deployments to verify the absence of exploitable injection points.