dbcve.org
Missing AuthorizationWeakness · CWE-862

CVE-2026-11858

HIGH · 8.4 CVSS v4.0 Published 2026-06-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
86/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Quanos SCHEMA ST4 Client Update Service runs as NT AUTHORITY\SYSTEM and exposes a .NET Remoting interface over a named pipe without proper access controls. A local authenticated low-privileged user can connect to this interface and invoke privileged methods like Update() to perform arbitrary file write and delete operations with SYSTEM privileges, achieving local privilege escalation.

MitigationRestrict access to the named pipe using Windows ACLs to prevent low-privileged users from connecting, implement proper authorization checks in the service, or reconfigure the service to run with reduced privileges.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
Authentication
X
User interaction
None
Scope
X

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm Quanos SCHEMA ST4 Client Update Service is installed
    Open Services console (services.msc) or run 'Get-Service' in PowerShell and look for a service named 'SCHEMA ST4 Client Update Service' or similar Quanos/Schema update service
    Affected if The service exists in the system services list
  2. Verify service runs as NT AUTHORITY\SYSTEM
    In Services console, right-click the service and select Properties, or run 'Get-WmiObject Win32_Service | Where-Object {$_.Name -like "*Schema*" -or $_.Name -like "*ST4*"} | Select-Object Name, StartName, StartMode' in PowerShell
    Affected if The 'Log On As' value shows NT AUTHORITY\SYSTEM or the equivalent string
  3. Identify the named pipe endpoint
    Use a tool like PipeList from Sysinternals (pipelist.exe) or run 'Get-ChildItem \\.\pipe\' in PowerShell to enumerate named pipes, looking for pipes associated with the SCHEMA ST4 service
    Affected if A named pipe created by the SCHEMA ST4 update service is present and exposed
  4. Test unauthenticated access to the Remoting interface
    Using a low-privilege account, attempt to connect to the named pipe using .NET Remoting client code or a tool like PowerShell with [System.Runtime.Remoting.Channels.Ipc.IpcClientChannel] to see if authentication is enforced
    Affected if A local authenticated user with minimal privileges can connect to the pipe without being prompted for credentials or denied access
  5. Check for vulnerable method exposure
    If the pipe is accessible, attempt to invoke the Update() method through the Remoting interface using a test client to verify if arbitrary file operations are possible
    Affected if The Update() method or similar privileged methods can be invoked to perform file write or delete operations

A system is affected if the Quanos SCHEMA ST4 Client Update Service is installed, runs as NT AUTHORITY\SYSTEM, exposes an accessible named pipe with .NET Remoting interface that allows unauthenticated or low-privilege users to invoke privileged file operations.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Restrict access to the named pipe using Windows ACLs to prevent low-privileged users from connecting, implement proper authorization checks in the service, or reconfigure the service to run with reduced privileges.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,690
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-11858 in production — separate from our analysis above.

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What this is

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What belongs here
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