CVE-2024-47263: Synology Hyper Backup Path Traversal – Admin Privilege Required

Technical summary

CVE-2024-47263 is a CWE-22 path traversal vulnerability in the Backup.Repository webapi component of Synology Hyper Backup prior to version 4.1.2-4036. The flaw permits remote authenticated users holding administrator privileges to manipulate file paths and write files to locations outside the application's restricted directory. The CVSS 3.1 vector (4.1/MEDIUM) reflects the requirement for high-privilege authentication and the integrity impact limited to non-sensitive information, with no confidentiality or availability breach. Exploitation does not require user interaction.

Business impact

While the immediate damage potential is modest due to file-write restrictions on non-sensitive data, this vulnerability undermines the separation of duties and blast-radius containment expected in backup infrastructure. Synology Hyper Backup is critical for disaster recovery; compromise of its API layer could enable an insider or compromised admin account to inject files into unexpected locations, potentially staging subsequent attacks or poisoning backup metadata. Organizations relying on Hyper Backup as a last line of defense should treat admin-account integrity as high priority.

Affected systems

Synology Hyper Backup versions prior to 4.1.2-4036 are affected. The vulnerability is specific to the Backup.Repository webapi component and requires the attacker to already possess administrator credentials. Synology NAS systems and any host running Hyper Backup as a standalone backup management platform are in scope.

Exploitability

Exploitation requires authenticated access with administrator privileges and can be performed over the network without user interaction. However, the attacker must already have compromised or possessed legitimate admin credentials—this is not an unauthenticated remote code execution vector. The CVSS score of 4.1 reflects this gatekeeping. Real-world risk escalates significantly in environments with weak credential hygiene, shared admin accounts, or lateral-movement paths from compromised endpoints.

Remediation

Upgrade Synology Hyper Backup to version 4.1.2-4036 or later. Verify the patched version number against the official Synology security advisory before deployment. Additionally, implement credential management best practices: enforce unique, strong admin passwords; enable multi-factor authentication where available; restrict admin account usage to necessary operations; and monitor admin API activity for anomalies.

Patch guidance

Download and install Synology Hyper Backup 4.1.2-4036 or a later version from the official Synology support portal. If you operate a NAS environment, verify compatibility with your current DSM version before patching. Test the upgrade in a non-production environment first to ensure backup continuity. Review your backup logs post-patch to confirm normal operation. For air-gapped or critical backup systems, coordinate patch deployment with your change management and disaster-recovery windows.

Detection guidance

Monitor Hyper Backup API logs for unusual file-write operations initiated by administrator accounts, particularly writes to non-standard or parent directories. Alert on path traversal indicators such as '../' or encoded equivalents in API request parameters. Correlate admin API access with known maintenance windows; unexpected usage outside business hours warrants investigation. Consider implementing file-integrity monitoring on the directories where Hyper Backup stores configuration and backup metadata to detect unauthorized modifications.

Why prioritize this

Although the CVSS score is moderate (4.1), prioritize patching in environments where backup systems are attack targets or where admin-account compromise has occurred recently. Backup infrastructure is a critical control; even low-severity boundary violations warrant prompt remediation. Organizations with mature credential monitoring and zero-trust architectures can apply a standard patch cycle. Environments with shared admin accounts or legacy access controls should treat this as higher priority.

Risk score, explained

The CVSS 3.1 score of 4.1 (MEDIUM) reflects: (1) network accessibility with low complexity, (2) mandatory high-privilege authentication requirement, (3) limited integrity impact (non-sensitive files only), and (4) no confidentiality or availability impact. The 'C' suffix in the vector indicates cross-zone scope change, acknowledging the API's network exposure, but the admin-authentication gate and narrow file-write scope cap the overall severity. In isolation, the score is appropriate; in context of backup criticality, organizational risk may be higher.

Frequently asked questions