CVE-2026-11858 Missing authorization in Quanos SCHEMA ST4 Client Update Service allows arbitrary file overwrite as SYSTEM
A local attacker can exploit missing authorization in the SCHEMA ST4 Client Update Service to overwrite files and escalate privileges to SYSTEM.
- 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-2026-11858?
CVE-2026-11858 is a high-severity missing authorization 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. The update service 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.
Weakness: CWE-862
Which versions are affected by CVE-2026-11858?
How do I fix CVE-2026-11858?
No fix has been published for CVE-2026-11858 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-11858 being exploited?
There is no known exploitation of CVE-2026-11858 in the wild and no public exploit code.
Sources
Also known as GHSA-62mq-g5fg-59fx.