CVE-2025-66593

Vulnerability

An origin validation error vulnerability (CWE-346) exists in Synology Assistant versions before 7.0.6-50085. The flaw occurs during the installation process, where the software fails to properly validate the origin of data or commands, allowing a local user to write arbitrary files with restricted content. Affected versions are all prior to 7.0.6-50085 [1].

Exploitation

To exploit this vulnerability, an attacker must have local access to the system running Synology Assistant. No authentication or user interaction beyond initiating the installation process is required, as the flaw is triggered during the normal installation flow. The attacker can inject or manipulate data to cause the Assistant to write files to arbitrary locations on the system [1].

Impact

Successful exploitation allows a local attacker to write arbitrary files, albeit with restricted content (likely limited to certain file types or data). This could lead to partial integrity loss and a high availability impact, as writing files to critical system paths may disrupt normal operations or cause denial of service. The CVSS v3.1 score is 6.1 (Medium), with the vector AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H [1].

Mitigation

Synology has released a fixed version: Synology Assistant 7.0.6-50085 or above. Users should upgrade to this version immediately. No workarounds are provided in the advisory. The vulnerability is not listed as known to be exploited in the wild (KEV) at the time of disclosure [1].