MBS vulnerabilities and threats

An administrator may attempt to block all networks by specifying "\*" or "all" as the network identifier. However, these values are not supported and do not trigger any validation error. Instead, they are silently interpreted as network 0 which results in no networks being blocked at all.

CVE-2025-41758 is a high-severity path traversal vulnerability in the MBS UBR-01 Mk II device, exploitable via the wwupload.cgi endpoint. A low-privileged remote attacker can leverage this flaw to perform arbitrary file writes, potentially overwriting critical system files. This can lead to full system compromise without requiring user interaction. The vulnerability stems from improper limitation of pathname inputs, classified under CWE-22. Although no public exploits are currently known, the CVSS score of 8.8 indicates a significant risk. The affected product is a specialized device, and no patches have been released yet. Organizations using this device should prioritize mitigation to prevent unauthorized access and control. The threat is particularly relevant to countries with deployments of MBS UBR-01 Mk II devices in critical infrastructure or enterprise environments.

A low-privileged remote attacker can abuse the backup restore functionality of UBR (ubr-restore) which runs with elevated privileges and does not validate the contents of the backup archive to create or overwrite arbitrary files anywhere on the system.

A low-privileged remote attacker can exploit the ubr-editfile method in wwwubr.cgi, an undocumented and unused API endpoint to write arbitrary files on the system.

A low-privileged remote attacker can exploit the ubr-logread method in wwwubr.cgi to read arbitrary files on the system. The endpoint accepts a parameter specifying the log file to open (e.g., /tmp/weblog{some_number}), but this parameter is not properly validated, allowing an attacker to modify it to reference any file and retrieve its contents.

A low-privileged remote attacker can exploit the ubr-editfile method in wwwubr.cgi, an undocumented and unused API endpoint to read arbitrary files on the system.