CVE-2025-62842 is a vulnerability categorized under CWE-73 (External Control of File Name or Path) affecting QNAP Systems Inc.'s HBS 3 Hybrid Backup Sync software, specifically version 26.1.x. This vulnerability allows an attacker with access to the local network to manipulate file names or paths processed by the software, enabling unauthorized reading or modification of files or directories. The flaw does not require any authentication or user interaction, which lowers the barrier to exploitation. The vulnerability impacts confidentiality, integrity, and availability by potentially exposing sensitive backup data or allowing malicious modification of backup files, which could disrupt recovery processes. The CVSS 4.0 vector indicates the attack vector is local network (AV:P), with low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and high impact on confidentiality, integrity, and availability (C:H, I:H, A:H). The vulnerability has been addressed in HBS 3 Hybrid Backup Sync version 26.2.0.938 and later. No public exploits have been reported yet, but the risk remains significant due to the nature of the vulnerability and the critical role of backup systems in organizational resilience. The vulnerability is particularly concerning for organizations relying on QNAP NAS devices for backup and synchronization, as exploitation could lead to data breaches or loss of backup integrity.

For European organizations, the impact of CVE-2025-62842 can be substantial. Many enterprises and SMBs across Europe use QNAP NAS devices for critical backup and synchronization tasks. Exploitation could lead to unauthorized disclosure of sensitive data stored in backups, modification or deletion of backup files, and disruption of business continuity due to compromised backup integrity. This could affect compliance with data protection regulations such as GDPR, leading to legal and financial repercussions. The local network access requirement means that attackers would need to be inside the network or have compromised a device within the network perimeter, which is a realistic threat vector given the rise of insider threats and lateral movement by attackers. The vulnerability could also be leveraged as a foothold for further attacks within the network. Organizations in sectors with high data sensitivity, such as finance, healthcare, and government, are particularly at risk.

1. Immediately upgrade all affected QNAP HBS 3 Hybrid Backup Sync installations to version 26.2.0.938 or later to apply the official patch. 2. Implement strict network segmentation to isolate backup devices from general user networks, limiting local network access to trusted administrators only. 3. Enforce strong access controls and monitoring on NAS devices, including disabling unnecessary services and restricting management interfaces to secure VLANs or VPNs. 4. Regularly audit network devices and logs for unusual access patterns that could indicate exploitation attempts. 5. Employ network intrusion detection/prevention systems (IDS/IPS) to detect suspicious activities targeting NAS devices. 6. Educate internal staff about the risks of local network threats and enforce policies to reduce insider threat risks. 7. Maintain regular offline backups to ensure recovery capability in case of backup data compromise. 8. Review and harden backup synchronization configurations to minimize exposure to path traversal or file manipulation attacks.