CVE-2025-62840 is a vulnerability identified in QNAP Systems Inc.'s HBS 3 Hybrid Backup Sync software, specifically affecting version 26.1.x. The issue is categorized under CWE-209, which involves the generation of error messages containing sensitive information. This vulnerability allows an attacker who has gained access to the local network to exploit the improper error handling mechanism to read sensitive application data. The flaw does not require authentication or user interaction, making it easier to exploit once local network access is obtained. The vulnerability could enable attackers to gather information that might facilitate further attacks or unauthorized data access. The CVSS 4.0 vector indicates a local network attack vector (AV:P), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and high impact on confidentiality, integrity, and availability (all rated high). QNAP has addressed this vulnerability in version 26.2.0.938 and later, urging users to update promptly. No known exploits have been reported in the wild yet, but the potential for sensitive data leakage makes this a significant concern for organizations relying on this backup solution. The vulnerability's presence in backup software is particularly critical as it may expose backup data or system configurations, increasing the risk of data breaches or ransomware attacks.

For European organizations, this vulnerability poses a significant risk to the confidentiality and integrity of backup data managed by QNAP HBS 3 Hybrid Backup Sync. Since backup data often contains critical business information and recovery points, unauthorized access could lead to data leakage, manipulation, or sabotage of backup sets. This could disrupt business continuity and increase exposure to ransomware or data theft. Organizations in sectors such as finance, healthcare, government, and critical infrastructure that rely heavily on QNAP NAS devices for backup and synchronization are particularly vulnerable. The requirement for local network access means that attackers may exploit weak internal network segmentation or compromised devices within the network. The vulnerability could also facilitate lateral movement within corporate networks, escalating the impact. Given the widespread use of QNAP devices in Europe, especially in small and medium enterprises and some public sector entities, the potential impact is substantial if patches are not applied promptly.

1. Immediately upgrade all QNAP HBS 3 Hybrid Backup Sync installations to version 26.2.0.938 or later to apply the official patch addressing CVE-2025-62840. 2. Restrict local network access to backup servers by implementing strict network segmentation and access controls, limiting exposure to only trusted devices and users. 3. Monitor network traffic and logs for unusual access patterns or error messages generated by HBS 3 services that could indicate exploitation attempts. 4. Employ intrusion detection/prevention systems (IDS/IPS) tuned to detect anomalous behavior related to backup synchronization processes. 5. Conduct regular security audits of backup infrastructure to ensure no unauthorized devices or users have local network access. 6. Educate IT staff about the risks of information leakage through error messages and the importance of timely patch management. 7. Consider deploying endpoint security solutions on devices within the local network to detect and prevent lateral movement by attackers. 8. Review and harden configuration settings of QNAP NAS devices to minimize unnecessary service exposure and disable unused features.