Overview
A high-severity vulnerability, identified as CVE-2025-8693, has been discovered in Zyxel DX3300-T0 routers running firmware version 5.50(ABVY.6.3)C0 and earlier. This vulnerability allows an authenticated attacker to execute arbitrary operating system (OS) commands on the affected device. This poses a significant security risk to users of these routers.
Technical Details
The vulnerability stems from a post-authentication command injection flaw in the handling of the “priv” parameter. Specifically, the application fails to properly sanitize user-supplied input to the ‘priv’ parameter, allowing an attacker with valid credentials to inject and execute arbitrary OS commands with elevated privileges. Exploitation requires successful authentication, but once authenticated, the attacker can gain full control of the router. The impacted endpoint is not specified in this advisery.
CVSS Analysis
The Common Vulnerability Scoring System (CVSS) assigns this vulnerability a score of 8.8, indicating a High severity. This score reflects the ease of exploitation (after authentication) and the significant impact on the affected device, including potential data compromise, system compromise, and denial of service.
Possible Impact
Successful exploitation of CVE-2025-8693 can lead to several critical consequences:
- Complete System Compromise: An attacker can gain full control over the affected router, allowing them to modify settings, install malware, and monitor network traffic.
- Data Theft: Sensitive data transmitted through the router, such as login credentials and personal information, can be intercepted and stolen.
- Botnet Recruitment: The compromised router can be added to a botnet and used to launch attacks against other systems.
- Denial of Service: An attacker can disrupt the router’s functionality, preventing legitimate users from accessing the internet.
- Network Pivoting: Once the router is compromised, an attacker could use it as a pivot point to gain access to other devices on the network.
Mitigation and Patch Steps
Zyxel has released a security advisory addressing this vulnerability. Users of Zyxel DX3300-T0 routers running firmware version 5.50(ABVY.6.3)C0 and earlier are strongly advised to take the following steps:
- Update Firmware: Immediately update the router’s firmware to the latest version available from Zyxel. Check the Zyxel support website for the appropriate firmware update for your specific model.
- Monitor for Suspicious Activity: Review router logs for any unusual activity, such as unauthorized access attempts or unexpected system changes.
- Strong Passwords: Ensure that you are using strong, unique passwords for your router’s administrative interface and Wi-Fi network.
- Disable Remote Management: If you do not need remote access to your router, disable the remote management feature.
