CVE-2026-11858 Quanos Solutions GmbH CVE debrief

Who should care

Administrators and users of Quanos SCHEMA ST4 on-premises should be aware of this vulnerability and take necessary actions to mitigate it. This vulnerability can be used to achieve local privilege escalation, which can lead to unauthorized access and control of the system. Security teams and vulnerability management teams should prioritize this vulnerability and ensure that affected systems are patched or mitigated.

Technical summary

The Client Update Service in Quanos SCHEMA ST4 on-premises runs as NT AUTHORITY SYSTEM and exposes a .NET Remoting interface over a named pipe without sufficient access controls or authorization. A local authenticated low-privileged user can connect to the interface and invoke privileged update methods such as Update(). This allows arbitrary file write and delete operations with SYSTEM privileges and can be used to achieve local privilege escalation. The vulnerability is caused by the lack of sufficient access controls or authorization on the .NET Remoting interface.

Defensive priority

High

Recommended defensive actions

• Apply the vendor's official patch or update to fix the vulnerability.
• Restrict access to the Client Update Service to authorized users only.
• Monitor system logs for suspicious activity related to the Client Update Service.
• Implement additional security controls to prevent local privilege escalation.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The CVE record was published on 2026-06-17T13:19:33.807Z and has not been modified since then. The NVD entry is currently Deferred. There is limited information available about the vulnerability, and defenders should verify the affected scope and severity with the vendor. The Client Update Service runs as NT AUTHORITY SYSTEM and exposes a .NET Remoting interface over a named pipe without sufficient access controls or authorization, allowing a local authenticated low-privileged user to connect to the interface and invoke privileged update methods such as Update().

Official resources