Local Privilege Escalation Vulnerability in Quanos SCHEMA ST4 On-Premises

CVE-2026-11857

What is CVE-2026-11857?

Quanos SCHEMA ST4 on-premises contains a local privilege escalation issue within its Client Update Service, primarily caused by insecure deserialization processes in the .NET Remoting service. The vulnerability arises due to the service's configuration with TypeFilterLevel.Full, which allows authenticated local users to exploit the service. By connecting through local named pipes, an attacker can access the .NET Remoting endpoint and transmit specially crafted serialized objects. If successful, this results in arbitrary code execution with the highest privileges, specifically NT AUTHORITY\SYSTEM, during the update process. Remote attacks are not feasible; therefore, access requires an authenticated user session on the local host.

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