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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2026-11857

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 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.

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 contains an insecure deserialization vulnerability in its .NET Remoting implementation. The service is configured with TypeFilterLevel.Full and exposed only via local named pipes. A local authenticated attacker can connect to this named pipe endpoint and send specially crafted serialized .NET objects that enable arbitrary code execution with NT AUTHORITY\SYSTEM privileges.

MitigationRestrict access to the vulnerable named pipe endpoint and implement proper authorization checks on the Client Update Service. Consider disabling TypeFilterLevel.Full if possible or upgrading to a patched version when available.

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. Identify if Quanos SCHEMA ST4 is installed
    Check for Quanos SCHEMA ST4 installation directory, typically under Program Files or Program Files (x86), or look for the product in Windows Add/Remove Programs
    Affected if Quanos SCHEMA ST4 Client Update Service is present on the system
  2. Verify the Client Update Service is running
    Open Services.msc and look for a service related to 'Schema ST4 Client Update' or check via command: Get-Service | Where-Object {$_.DisplayName -like '*Schema*Client*Update*'}
    Affected if The Client Update Service exists and is running
  3. Confirm the service runs under NT AUTHORITY\SYSTEM
    Right-click the service in Services.msc and select Properties, or run: wmic service where "name like '%Schema%'" get Name,StartName,State
    Affected if The service runs with NT AUTHORITY\SYSTEM privileges
  4. Identify the named pipe endpoint configuration
    Examine the application configuration files (App.config or XML config files) in the SCHEMA ST4 installation directory for .NET Remoting configuration and named pipe bindings
    Affected if The service exposes a named pipe endpoint with .NET Remoting configured
  5. Check for TypeFilterLevel.Full setting
    Search the configuration files for 'TypeFilterLevel' set to 'Full' in the .NET Remoting <channels> or <serverProviders> section
    Affected if TypeFilterLevel.Full is configured, which enables full deserialization of .NET objects

A user is affected if the Quanos SCHEMA ST4 Client Update Service is installed, running under NT AUTHORITY\SYSTEM, and exposes a .NET Remoting named pipe endpoint with TypeFilterLevel.Full enabled.

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 vulnerable named pipe endpoint and implement proper authorization checks on the Client Update Service. Consider disabling TypeFilterLevel.Full if possible or upgrading to a patched version when available.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2026-11857 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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  • Version or environment caveats, and links to real fixes
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