The most serious vulnerability is located in the Synology Photo Station, a feature of DiskStation Manager (DSM), the Linux-based operating system that runs on the company's NAS devices.
Synology Photo Station allows users to create online photo albums and blogs that can be accessed remotely using the NAS device's public IP (Internet Protocol) address.
Researchers from Dutch firm Securify found that Photo Station did not properly sanitize user input, allowing potential attackers to inject system commands that would be executed with the privileges of the Web server.
In addition, Photo Station does not have protection against cross-site request forgery (CSRF), a technique that allows a website to force a visitor's browser to execute malicious actions on a different website.
So even if Photo Station is not configured to be accessible from the Internet, an attacker could trick a user located on the same network as the NAS device to visit a specially crafted Web page that would use CSRF to exploit the command inject vulnerability over the LAN.
By leveraging this flaw attackers could compromise the NAS device, including all data stored on it, the researchers said in an advisory that also includes a proof-of concept exploit.
Synology fixed this vulnerability last week in version 6.3-2945 of Photo Station. However, the release notes only mention "security enhancements" with no additional details.
The new version also addressed two cross-site scripting (XSS) vulnerabilities that were identified by the Securify researchers.
Those vulnerabilities could be exploited by tricking Photo Station users into opening a specially crafted URL that would execute rogue code in their browsers. Successful attacks could allow attackers to steal the session tokens or login credentials of targeted Photo Station users or to execute arbitrary actions on their behalf.
A similar vulnerability was also patched by Synology last week in the management interface of DiskStation Manager. Users are advised to upgrade to DSM version 5.2-5565 Update 1.
Synology NAS devices have been targeted by hackers in the past. Last year attackers exploited a vulnerability to infect many such devices with a file-encrypting ransomware program and previously hackers compromised Synology devices to run cryptocurrency mining programs on them.