Overview
CVE-2025-29843 describes a medium-severity vulnerability affecting Synology FileStation. This flaw allows remote, authenticated users to potentially read and write image files on the system. The vulnerability stems from an issue within the thumb cgi component of FileStation.
Technical Details
The vulnerability lies within the `thumb.cgi` application of Synology FileStation. Due to insufficient input validation and authorization checks, a remote attacker with valid user credentials can manipulate requests to `thumb.cgi` to access or modify image files beyond their intended permissions. The specifics of the exploit depend on the vulnerable version of FileStation, but generally involve crafting malicious requests that bypass access control mechanisms. Further details on the specific attack vectors are likely available in the linked Synology security advisory.
CVSS Analysis
The vulnerability has a CVSS v3 score of 5.4, indicating a medium severity. The CVSS vector is likely along the lines of AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N. This translates to:
- Attack Vector (AV:N): Network – The vulnerability is exploitable over the network.
- Attack Complexity (AC:L): Low – Exploitation requires minimal effort.
- Privileges Required (PR:L): Low – An attacker needs only low-level privileges (e.g., valid user account).
- User Interaction (UI:N): None – No user interaction is required for exploitation.
- Scope (S:U): Unchanged – The vulnerability affects only the vulnerable component.
- Confidentiality Impact (C:L): Low – Limited access to confidentiality is possible. Image files may be read.
- Integrity Impact (I:L): Low – Limited modification to integrity is possible. Image files may be written/modified.
- Availability Impact (A:N): None – There is no impact on system availability.
Possible Impact
Successful exploitation of CVE-2025-29843 could have the following consequences:
- Unauthorized Access to Images: Attackers could gain access to sensitive image files stored on the NAS.
- Image Modification/Defacement: Attackers could modify existing images, potentially causing reputational damage or data corruption.
- Data Breach: In scenarios where images contain sensitive information (e.g., documents, scans), this vulnerability could contribute to a data breach.
Mitigation & Patch Steps
The primary mitigation strategy is to update Synology FileStation to the latest available version, which includes a patch for CVE-2025-29843. Follow these steps:
- Log in to your Synology NAS DSM (DiskStation Manager).
- Open the Package Center.
- Search for “FileStation”.
- If an update is available, click “Update”.
- After updating, restart your Synology NAS to ensure the patch is fully applied.
It’s also recommended to practice good security hygiene, such as using strong passwords and enabling two-factor authentication (2FA) for all user accounts.
