CVE-2025-1021 is a missing authorization vulnerability identified in the Synology DiskStation Manager (DSM) software, specifically affecting versions prior to 7.1.1-42962-8, 7.2.1-69057-7, and 7.2.2-72806-3. The vulnerability resides in the 'synocopy' component of DSM, which is responsible for file copying and management operations. Due to improper authorization checks, remote attackers can exploit this flaw to read arbitrary files on the affected system without requiring authentication. The exact attack vectors have not been publicly detailed, but the vulnerability allows unauthorized access to potentially sensitive files stored on the NAS device. This could include configuration files, user data, or system credentials. The flaw does not appear to allow modification or deletion of files, but unauthorized disclosure of data can lead to further attacks such as credential theft or lateral movement within a network. No known exploits are currently observed in the wild, and Synology has not yet published official patches or detailed mitigation guidance. The vulnerability was reserved in early February 2025 and publicly disclosed in late April 2025, indicating a relatively recent discovery. Given the nature of the vulnerability, it primarily impacts confidentiality and partially impacts integrity due to the potential for information leakage. The vulnerability does not require user interaction but can be exploited remotely, increasing its risk profile. Since the vulnerability affects multiple recent DSM versions, a broad range of Synology NAS devices are potentially vulnerable until updated firmware is applied.

For European organizations, the impact of CVE-2025-1021 can be significant, especially for those relying on Synology NAS devices for file storage, backup, and collaboration. Unauthorized file access can lead to exposure of sensitive corporate data, intellectual property, or personal data protected under GDPR, resulting in compliance violations and potential fines. The breach of confidentiality may also facilitate further attacks such as phishing, ransomware, or network infiltration. Organizations in sectors such as finance, healthcare, legal, and government are particularly at risk due to the sensitivity of their stored data. Additionally, the disruption caused by data leakage incidents can damage organizational reputation and trust. Since Synology devices are often used in small to medium enterprises and remote office environments, the vulnerability could be exploited to gain footholds in less monitored network segments. The absence of known exploits currently provides a window for proactive mitigation, but the ease of remote exploitation without authentication means attackers could rapidly weaponize this flaw once details become widespread.

1. Immediate firmware update: Organizations should prioritize upgrading Synology DSM to versions 7.1.1-42962-8, 7.2.1-69057-7, or 7.2.2-72806-3 or later once official patches are released by Synology. 2. Network segmentation: Isolate NAS devices from public-facing networks and restrict access to trusted internal IP ranges to reduce exposure. 3. Access control hardening: Enforce strict firewall rules and VPN-only access to DSM management interfaces. 4. Monitor logs: Enable and review DSM access logs for unusual file access patterns or unauthorized connection attempts. 5. Disable unnecessary services: Temporarily disable synocopy or related file management services if feasible until patches are applied. 6. Data encryption: Ensure sensitive data stored on NAS devices is encrypted at rest and in transit to mitigate data exposure risks. 7. Incident response readiness: Prepare to investigate and respond to potential data leakage incidents by maintaining backups and forensic capabilities. 8. Vendor communication: Maintain close contact with Synology for timely updates and advisories. These measures go beyond generic advice by focusing on network-level controls, service hardening, and proactive monitoring tailored to the specific vulnerability context.