CVE-2025-13593: Synology ActiveProtect Privilege Escalation

CVE-2025-13593 Overview

CVE-2025-13593 is an origin validation error [CWE-346] in Synology ActiveProtect Agent versions prior to 1.1.0-0439. The flaw allows local users to write arbitrary files with restricted content during installation. Exploitation requires local access and user interaction, limiting remote attack scenarios. The vulnerability impacts integrity and availability but does not directly expose confidential data.

Critical Impact

Local users can write arbitrary files with restricted content during installation of the Synology ActiveProtect Agent, potentially impacting system integrity and availability.

Affected Products

• Synology ActiveProtect Agent versions before 1.1.0-0439
• Endpoints running the ActiveProtect Agent installer
• Systems where local users can invoke the installation process

Discovery Timeline

• 2026-05-27 - CVE-2025-13593 published to NVD
• 2026-05-27 - Last updated in NVD database

Technical Details for CVE-2025-13593

Vulnerability Analysis

The vulnerability resides in the installation routine of the Synology ActiveProtect Agent. The installer fails to properly validate the origin of file write operations. This origin validation error [CWE-346] permits a local user to direct the installer to write files into locations outside the intended scope. The written content is restricted in form, but the file path and presence can be controlled. The flaw is local in nature and requires user interaction, which constrains exploitation to scenarios where an attacker already has interactive access. The integrity impact is limited, while the availability impact is high because attackers can overwrite or place files that disrupt service operations.

Root Cause

The root cause is improper validation of the origin of installation actions. The installer trusts inputs or contexts that should be authenticated against an expected source. Without strict origin checks, the installer accepts directives that lead to arbitrary file writes during the privileged install phase.

Attack Vector

A local user triggers the installation workflow of the ActiveProtect Agent. The attacker manipulates the installer's trusted inputs so that file write operations target unintended paths. User interaction is required, and successful exploitation can result in disruption of system services or applications dependent on the overwritten files. Refer to the Synology Security Advisory SA-25-15 for vendor-supplied technical context.

Detection Methods for CVE-2025-13593

Indicators of Compromise

• Unexpected files created or overwritten in system directories during or after an ActiveProtect Agent installation
• ActiveProtect Agent installer processes spawning file operations outside the expected installation directory
• Installation logs referencing non-standard file paths or unexpected write targets

Detection Strategies

• Monitor file system telemetry for write operations originating from the ActiveProtect Agent installer that target paths outside its installation scope
• Audit process lineage for installer executions invoked by non-administrative local users
• Compare deployed ActiveProtect Agent versions against the patched baseline of 1.1.0-0439

Monitoring Recommendations

• Forward installer execution and file write events to a centralized logging or SIEM platform for correlation
• Establish alerts for installer-related file modifications in protected directories
• Track version inventory across endpoints to identify unpatched ActiveProtect Agent deployments

How to Mitigate CVE-2025-13593

Immediate Actions Required

• Upgrade Synology ActiveProtect Agent to version 1.1.0-0439 or later on all affected endpoints
• Restrict the ability to execute the ActiveProtect Agent installer to trusted administrators
• Review recent installations of the agent for signs of unexpected file writes

Patch Information

Synology has released a fixed version of the ActiveProtect Agent. Apply version 1.1.0-0439 or later. Consult the Synology Security Advisory SA-25-15 for vendor guidance and the official release.

Workarounds

• Limit local user access on systems where ActiveProtect Agent is installed to reduce the population of potential attackers
• Block execution of the vulnerable installer version using application control policies until patching is complete
• Require administrative supervision for any ActiveProtect Agent installation or upgrade activity

# Verify installed ActiveProtect Agent version meets the patched baseline
activeprotect-agent --version
# Expected: 1.1.0-0439 or later