CVE-2026-31850 is a vulnerability identified in Nexxt Solutions Nebula 300+ routers with firmware versions up to 12.01.01.37. The flaw arises from the device's practice of storing sensitive data such as administrative credentials and WiFi pre-shared keys in plaintext within exported configuration backup files. These backup files are typically used for device configuration management and disaster recovery. Because the sensitive information is not encrypted or otherwise protected, anyone who can obtain these backup files can retrieve critical secrets, potentially leading to unauthorized administrative access and network compromise. The vulnerability is classified under CWE-256, which pertains to the plaintext storage of passwords. According to the CVSS 4.0 vector, the attack requires adjacent network access (AV:A) and high privileges (PR:H) but does not require user interaction (UI:N). The vulnerability impacts confidentiality with high scope (VC:H), but does not affect integrity or availability. No patches have been linked yet, and no known exploits are reported in the wild. This vulnerability highlights a significant security design weakness in the handling of sensitive configuration data by the affected firmware versions.

The primary impact of this vulnerability is the compromise of confidentiality. If an attacker gains access to exported configuration backup files, they can extract administrative credentials and WiFi pre-shared keys in plaintext, enabling unauthorized device and network access. This can lead to further lateral movement within the network, data exfiltration, or disruption of network services. Although exploitation requires authenticated access to the device to export the configuration, insider threats or attackers who have gained limited access could leverage this vulnerability to escalate privileges. The exposure of WiFi keys also risks unauthorized wireless network access, potentially bypassing perimeter defenses. Since the vulnerability does not affect integrity or availability directly, the immediate risk is unauthorized access and information disclosure. Organizations relying on Nexxt Solutions Nebula 300+ devices in critical infrastructure, SMBs, or enterprise environments could face significant operational and reputational damage if exploited.

1. Restrict access to the device management interface to trusted administrators only, using network segmentation and strong authentication controls. 2. Avoid exporting configuration backups unless absolutely necessary, and securely store any exported files with encryption and access controls. 3. Monitor and audit access to configuration backups to detect unauthorized exports. 4. Implement strict physical and logical security controls to prevent unauthorized access to devices and backup files. 5. Regularly check for firmware updates from Nexxt Solutions and apply patches promptly once available. 6. Consider using alternative secure configuration management tools or methods that do not expose plaintext credentials. 7. Educate administrators about the risks of plaintext credential storage and enforce policies for secure handling of configuration files. 8. If possible, rotate administrative and WiFi credentials after exporting backups to limit exposure duration.