CVE-2026-75163: MBS-Solutions X-Serie Gateway Disclosure

CVE-2026-75163 Overview

CVE-2026-75163 is an information disclosure vulnerability in the ugw-deviceinfo method of /cgi-bin/wwwugw.cgi in MBS-Solutions X-Serie Gateway firmware V6_00_05. The endpoint returns detailed system version fields, including operatingsystem and gatewayversion, to any authenticated user. Accounts holding the low-privileged Standard role can retrieve the same data intended for administrative visibility. The flaw maps to CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.

Critical Impact
Any authenticated user, including Standard-role accounts, can enumerate firmware and operating system version data useful for targeted follow-on exploitation of the gateway.

Affected Products

MBS-Solutions X-Serie Gateway firmware V6_00_05
/cgi-bin/wwwugw.cgi handler exposing the ugw-deviceinfo method
Deployments where the Standard user role is provisioned for non-administrative users

Discovery Timeline

2026-09-04 - CVE-2026-75163 published to the National Vulnerability Database
2026-09-08 - Last updated in NVD database

Technical Details for CVE-2026-75163

Vulnerability Analysis

The ugw-deviceinfo method in /cgi-bin/wwwugw.cgi performs authentication but does not enforce role-based authorization on the response payload. Standard-role users receive the same detailed system inventory as administrative users. The returned fields include the underlying operating system identifier and the gateway firmware version, both of which support fingerprinting of the appliance.

Information disclosure at this layer changes the economics of downstream attacks. Adversaries who compromise a low-privileged account, or who obtain credentials from a shared user population, can map the exact firmware build in use. That build identifier can then be correlated against known vulnerabilities affecting the X-Serie platform without any additional probing.

The issue is exploitable over the network against the gateway's management interface. No user interaction is required beyond the authenticated request itself.

Root Cause

The root cause is missing authorization on privileged data returned by an authenticated CGI method. The handler validates that a session exists but does not restrict the operatingsystem and gatewayversion fields to administrative roles. The Standard role therefore inherits visibility that should be scoped to higher-privileged users.

Attack Vector

An attacker requires a valid Standard-role account on the target X-Serie Gateway. The attacker issues an authenticated request to /cgi-bin/wwwugw.cgi invoking the ugw-deviceinfo method. The response contains firmware and operating system version fields that enable precise version fingerprinting for follow-on targeting. Full technical details are documented in the GitHub CVE-2026-75163 Research repository.

Detection Methods for CVE-2026-75163

Indicators of Compromise

Authenticated HTTP requests to /cgi-bin/wwwugw.cgi invoking the ugw-deviceinfo method from non-administrative sessions.
Repeated ugw-deviceinfo calls from a single Standard-role session, indicating reconnaissance scripting.
Requests to the CGI endpoint originating from unexpected IP ranges or off-hours workstations.

Detection Strategies

Enable verbose access logging on the gateway's web server and forward logs to a centralized SIEM for correlation.
Build detections that flag ugw-deviceinfo invocations by users whose assigned role is Standard rather than Administrator.
Correlate device-info retrievals with subsequent authentication anomalies or configuration probes from the same account.

Monitoring Recommendations

Baseline the population of user accounts that legitimately query ugw-deviceinfo and alert on new principals.
Monitor for enumeration patterns where multiple gateways are queried by the same source within a short window.
Review Standard-role account activity periodically for access to endpoints outside their documented job function.

How to Mitigate CVE-2026-75163

Immediate Actions Required

Audit all Standard-role accounts on X-Serie Gateway V6_00_05 and disable accounts that are unused or over-provisioned.
Restrict management-interface reachability to trusted administrative networks using firewall or VPN controls.
Rotate credentials for any Standard-role account that may be shared across users or systems.
Contact MBS-Solutions through the MBS Solutions Overview page to confirm patch availability for the MBS XSerie Product Page line.

Patch Information

No vendor patch is referenced in the NVD entry at the time of publication. Operators should track vendor advisories for a fixed firmware release superseding V6_00_05 and apply it once available. Until a fix is published, treat the disclosed version fields as attacker-known and prioritize compensating controls.

Workarounds

Limit access to /cgi-bin/wwwugw.cgi at a reverse proxy or network layer so that only administrative source addresses can reach the endpoint.
Remove or downgrade Standard-role accounts that do not require gateway management access.
Enforce strong, unique passwords and multi-factor authentication on all gateway accounts to reduce the risk of credential compromise enabling the disclosure.
Segment the gateway's management VLAN from user networks to reduce exposure to internal reconnaissance.

bash

# Example: restrict access to the vulnerable CGI endpoint at an upstream proxy
# Only allow the administrative subnet 10.10.0.0/24 to reach ugw-deviceinfo
location /cgi-bin/wwwugw.cgi {
    allow 10.10.0.0/24;
    deny all;
    proxy_pass https://xserie-gateway.internal;
}