Vulnerability · Published Jun 17, 2026 · Assigned by SEC-VLab

CVE-2026-11858Missing authorization in Quanos SCHEMA ST4 Client Update Service allows arbitrary file overwrite as SYSTEM

High 8.4

In plain English

A high-severity missing authorization in SCHEMA ST4 from Quanos Solutions GmbH. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities).

Severity (CVSS 4.0)8.4High

Exploit odds (30 days)0.1%top 97.7% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

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.

Affected products (as reported)

Vendor	Product	Versions
Quanos Solutions GmbH	SCHEMA ST4	SCHEMA ST4 on-premises, all versions

Weakness: CWE-862 · Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

References

https://r.sec-consult.com/quanos third-party-advisory