Synology NFS Vulnerability Allows Unauthorized File Access

Synology has resolved a significant security vulnerability in its DiskStation Manager (DSM) software, which exposed users to the risk of unauthorized file access via the Network File System (NFS) service.

The flaw, tracked as CVE-2025-1021, was rated “Important” and affected multiple DSM versions, prompting urgent patch releases and advisories for all users.

Vulnerability Overview and Impact

The vulnerability stemmed from a missing authorization check in the synocopy component of DSM, specifically impacting writable NFS services.

This flaw allowed unauthenticated remote attackers to read arbitrary files on affected Synology NAS devices without needing user interaction or credentials.

As a result, sensitive data—including personal files and business documents—could be exposed to unauthorized parties.

The Common Vulnerability Scoring System (CVSS v3.1) assigned this issue a base score of 7.5, reflecting its seriousness.

The attack vector was network-based, with low complexity and no privileges required, making exploitation feasible for remote threat actors.

The vulnerability was responsibly disclosed by the DEVCORE Research Team, and Synology responded promptly with patches.

Affected Products and Patch Guidance

The table below summarizes the affected DSM versions and the corresponding fixed releases:

Product	Severity	Fixed Release Version
DSM 7.2.2	Important	7.2.2-72806-3 or above
DSM 7.2.1	Important	7.2.1-69057-7 or above
DSM 7.1	Important	7.1.1-42962-8 or above

Synology strongly urges all users of the affected DSM versions to upgrade immediately to the specified fixed releases or later.

There are no alternative mitigation strategies available; applying the update is the only way to secure vulnerable systems.

Disclosure Timeline and Security Lessons

The vulnerability was first publicly disclosed on February 26, 2025, with full technical details released on April 23, 2025, after patches were made available.

Synology’s coordinated response with security researchers helped minimize the potential impact of the flaw, but the incident highlights the ongoing importance of timely updates and vigilant monitoring of NAS devices—especially those using network file systems.

This case underscores the critical role of regular software updates and proactive security practices for both home and enterprise NAS environments.

Table: Synology DSM Vulnerability Summary

Aspect	Details
Vulnerability ID	CVE-2025-1021
Component	synocopy (NFS Service)
Severity	Important
CVSS v3.1 Score	7.5
Attack Vector	Network, no authentication required
Disclosure Date	2025-02-26 (initial), 2025-04-23 (full)
Reporter	DEVCORE Research Team

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