CVE-2026-31850 identifies a vulnerability in Nexxt Solutions Nebula 300+ routers running firmware versions up to 12.01.01.37, where sensitive data such as administrative passwords and WiFi pre-shared keys are stored in plaintext within exported configuration backup files. These backups are generated through legitimate device features intended for configuration management or recovery. However, the lack of encryption or hashing on these files means that anyone who can obtain them—whether through authorized access, interception, or exploitation of other weaknesses—can directly read and misuse the credentials. The vulnerability is classified under CWE-256, which relates to plaintext storage of passwords. The CVSS 4.0 score of 6.8 reflects a medium severity, with attack vector being adjacent network (AV:A), low attack complexity (AC:L), no privileges required for attack initiation (PR:H indicates high privileges required, so attacker must have elevated access), no user interaction, and high impact on confidentiality. The flaw does not affect integrity or availability directly but compromises confidentiality severely. No patches are currently linked, and no known exploits have been reported in the wild, but the exposure of plaintext credentials poses a significant risk if backup files are accessed by unauthorized parties. This vulnerability underscores the importance of secure credential storage and encrypted backups in network devices.

The primary impact of this vulnerability is the compromise of confidentiality, as attackers who gain access to the exported backup files can retrieve administrative credentials and WiFi pre-shared keys in plaintext. This can lead to unauthorized administrative access to the router, allowing attackers to modify configurations, intercept or redirect network traffic, and potentially pivot to other network resources. Exposure of WiFi keys also enables unauthorized wireless network access, increasing the attack surface. Although exploitation requires elevated privileges to access the backup functionality, the risk remains significant in environments where internal threats or lateral movement by attackers exist. Organizations relying on Nebula 300+ devices may face network breaches, data interception, and loss of control over network infrastructure. The absence of encryption in backups also raises concerns about data leakage during backup file transfer or storage. Given the widespread use of such devices in small to medium business and home networks, the vulnerability could facilitate broader compromise if exploited in targeted attacks.

To mitigate this vulnerability, organizations should first restrict access to the backup configuration functionality to trusted administrators only, ensuring that only authorized personnel can export configuration files. Network segmentation and strong access controls should be enforced to limit exposure of the device management interfaces. Until a firmware update addressing this issue is released, avoid storing or transferring backup files over insecure channels, and securely delete backup files after use. Monitoring and logging access to backup exports can help detect suspicious activity. Organizations should also consider changing administrative and WiFi credentials after exporting backups to reduce risk if files are compromised. When available, promptly apply firmware updates from Nexxt Solutions that implement encryption or hashing of sensitive data within backup files. Additionally, consider deploying network intrusion detection systems to identify unusual access patterns to the device management interfaces. Finally, educate administrators about the risks of plaintext credential storage and the importance of secure backup handling.