CVE-2025-29898 is a medium-severity vulnerability affecting QNAP Systems Inc.'s Qsync Central product, specifically version 4.5.x.x prior to 4.5.0.7. The vulnerability is classified under CWE-400, which corresponds to uncontrolled resource consumption, commonly leading to denial-of-service (DoS) conditions. The flaw allows a remote attacker who has already obtained a user account with limited privileges (low privileges) to exploit the vulnerability without requiring any user interaction. By triggering excessive resource consumption, the attacker can degrade or completely disrupt the availability of the Qsync Central service. The vulnerability does not impact confidentiality or integrity directly but targets availability. The CVSS 4.0 base score is 6.0, reflecting a medium severity level, with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), privileges required (PR:L), no user interaction (UI:N), and high impact on availability (VA:H). The vulnerability has been fixed in Qsync Central version 4.5.0.7 released on April 23, 2025. There are no known exploits in the wild reported at this time. The vulnerability arises from improper handling of resource allocation or consumption, allowing an authenticated user to trigger excessive use of system resources, potentially leading to service outages or degraded performance.

For European organizations using QNAP Qsync Central 4.5.x.x, this vulnerability poses a significant risk to service availability. Qsync Central is often used for file synchronization and collaboration, so a denial-of-service attack could disrupt business continuity, impede file access, and affect productivity. Since exploitation requires a valid user account, insider threats or compromised credentials could be leveraged to launch attacks. The impact is particularly critical for sectors relying on continuous access to synchronized data, such as finance, healthcare, and critical infrastructure. Additionally, disruption of Qsync services could indirectly affect compliance with data availability requirements under regulations like GDPR. While confidentiality and integrity are not directly impacted, the availability loss can cause operational and reputational damage. The absence of known exploits reduces immediate risk, but the medium severity and ease of exploitation with low privileges warrant prompt attention.

European organizations should immediately verify their Qsync Central version and upgrade to version 4.5.0.7 or later to remediate the vulnerability. Beyond patching, organizations should enforce strong authentication policies to reduce the risk of account compromise, including multi-factor authentication (MFA) for all Qsync users. Monitoring and logging of user activities on Qsync Central should be enhanced to detect unusual resource consumption patterns indicative of exploitation attempts. Network segmentation and access controls should limit Qsync Central access to trusted users and networks. Additionally, rate limiting or resource quotas could be implemented if supported by the platform to prevent resource exhaustion. Regular vulnerability scanning and penetration testing focused on Qsync Central deployments can help identify residual risks. Finally, organizations should maintain incident response plans that include procedures for mitigating DoS attacks on critical synchronization services.