CVE-2024-47273: Synology Hyper Backup Path Traversal Vulnerability (4.3 MEDIUM)

Technical summary

CVE-2024-47273 is a CWE-22 path traversal vulnerability affecting Synology Hyper Backup. The flaw exists in the Backup Task functionality and permits authenticated remote users to bypass directory restrictions and write files to arbitrary locations via unspecified vectors. The vulnerability requires valid authentication credentials and network access but does not require user interaction. The attack surface is limited to authenticated sessions, which reduces immediate exposure but increases risk in environments where account compromise is plausible.

Business impact

This vulnerability poses a moderate risk to organizations relying on Synology Hyper Backup for data protection workflows. A compromised administrative or service account could be leveraged to write malicious files, modify system configuration files, or inject code into application directories. For environments where backup infrastructure is trusted with sensitive data or system access, this creates potential for data exfiltration, system instability, or privilege escalation chains. The impact is heightened if backup credentials are shared, reused across systems, or stored insecurely.

Affected systems

Synology Hyper Backup versions prior to 4.1.2-4036 are affected. Organizations should verify their current deployment version against Synology's advisory to confirm exposure. The vulnerability affects the backup task feature, which is typically deployed in data center, SMB, or distributed backup scenarios. Virtual machine environments, NAS systems, and cloud backup orchestration platforms running vulnerable versions require immediate attention.

Exploitability

Exploitation requires valid authentication credentials and network connectivity to the Hyper Backup service. An attacker cannot exploit this remotely without legitimate account access. The CVSS vector (AV:N/AC:L/PR:L/UI:N/S:U) reflects low attack complexity once authentication is obtained. The integrity impact is limited (I:L), meaning successful exploitation compromises file integrity in restricted directories but does not enable confidentiality breaches or system availability attacks. The lack of widespread public exploit code and the need for valid credentials keep exploitability moderate in practice.

Remediation

Update Synology Hyper Backup to version 4.1.2-4036 or later. Verify this version number against Synology's official advisory and release notes before deployment. Apply updates during a maintenance window to avoid disruption to backup operations. After patching, audit backup task configurations and review access logs for any suspicious file write operations during the window of exposure.

Patch guidance

Synology provides patches through its standard update mechanism. Navigate to the Hyper Backup management interface, check for available updates, and apply version 4.1.2-4036 or later. For organizations with automatic update policies, verify that the deployment completed successfully and validate system functionality post-patch. Test backup task operations in a non-production environment before full rollout if possible. Confirm the patch version matches the advisory guidance to avoid incomplete remediation.

Detection guidance

Monitor Synology Hyper Backup audit logs for backup task operations by authenticated users, particularly file write operations outside expected backup destinations. Look for anomalous path construction patterns in task configurations or execution logs that reference system directories or configuration paths. Enable verbose logging on backup tasks if available. Review system file integrity logs for unexpected file modifications in restricted directories during the exposure window. Network-level detection should focus on suspicious outbound connections initiated by the Hyper Backup service following suspicious task execution.

Why prioritize this

This vulnerability rates MEDIUM severity and should not displace critical or high-risk patch campaigns, but it merits near-term remediation because (1) it affects a trusted system component with broad data access, (2) authenticated compromise scenarios are plausible in enterprise environments, and (3) exploitation could facilitate follow-on attacks. Organizations with strong access controls and limited backup credential distribution should prioritize this below critical CVEs but above low-severity issues. Those with shared or weak credential management should elevate priority.

Risk score, explained

The CVSS 3.1 score of 4.3 (MEDIUM) reflects the requirement for prior authentication (PR:L) and limited integrity impact (I:L). The lack of confidentiality or availability impact caps the score despite network accessibility and low attack complexity. This scoring appropriately represents the real-world risk: a meaningful but contained threat that requires credential compromise as a prerequisite. Organizations should not underweight this based on the score alone; context around credential hygiene and backup system exposure is critical.

Frequently asked questions