CVE-2026-11857 Insecure .NET Remoting deserialization in Quanos SCHEMA ST4 Client Update Service allows local privilege escalation
Local attackers can exploit insecure .NET Remoting deserialization in the update service to execute arbitrary code with SYSTEM privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-11857?
CVE-2026-11857 is a high-severity unsafe deserialization vulnerability in Quanos Solutions GmbH SCHEMA ST4, published on 17 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Quanos SCHEMA ST4 on-premises contains a local privilege escalation vulnerability in the Client Update Service due to insecure deserialization in the .NET Remoting service. The service is configured with TypeFilterLevel.Full and is bound to local interfaces only through named pipes. A local authenticated attacker can connect to the local named pipe, obtain the .NET Remoting endpoint, and send specially crafted serialized objects. Successful exploitation results in arbitrary code execution in the context of the update process with NT AUTHORITY\SYSTEM privileges. Network-only exploitation is not possible and local host access with an authenticated user session is required.
Weakness: CWE-502
Which versions are affected by CVE-2026-11857?
How do I fix CVE-2026-11857?
No fix has been published for CVE-2026-11857 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-11857 being exploited?
There is no known exploitation of CVE-2026-11857 in the wild and no public exploit code.
Sources
Also known as GHSA-fmx7-jmr3-4jw2.