The update is related to the Countercept Agent’s Ultralight Core. Ultralight Core provides low-level functionality such as file hash calculation as part of the agent’s reporting of endpoint activity.

Product Name: Countercept Agent for Windows – Ultralight Core

Version: 2.1.21134

Pilot Availability: 07/01/2026

General Availability: 14/01/2026

Predecessor: 2.1.21067

Release Purpose:

• General maintenance

Customer Action Required:

• The Operating System should be Azure Code Signing (ACS) compliant to receive this update. See
  
  https://community.withsecure.com/en/kb/articles/29714-changes-in-support-on-microsoft-windows-minimum-patch-level
  
  
  for more details.
  Any endpoints which are not ACS-compliant will continue to run the older version of the Ultralight Core (2.1.16183).

Name Changes:

• No changes to file, process, or service names.

Files Updated:

• CapricornScanner.exe
• fshoster64.exe
• fsulgk.sys
• install.exe
• uninstall.exe

New Features and Enhancements:

• N/A

General Maintenance:

• General maintenance of functionality not utilized by Countercept.

OS Support:

• Windows 10, 11
• Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2025

The update is related to the Countercept Agent’s Sensor component. The Sensor component gathers data to be analyzed in the WithSecure backend to identify any malicious activity. 

Product Name: Countercept Agent for Windows – Sensor Component

Version: 2025.3.64

Pilot Availability: 07/01/2026

General Availability: 21/01/2026

Predecessor: 2025.3.54

Release Purpose:

• Generic maintenance

Customer Action Required:

• The Operating System should be Azure Code Signing (ACS) compliant to receive this update. See 
  
  https://community.withsecure.com/en/kb/articles/29714-changes-in-support-on-microsoft-windows-minimum-patch-level
  
  
       for more details.
  Any endpoints which are not ACS-compliant will continue to run the previous production version of the sensor (2023.1.75).

Name Changes:

• No changes to file, process, or service names.

Files Updated:

• fsatp.sys
• fsatpl.exe
• fsatpn.exe
• install.exe
• sensor_control.exe

New Features and Enhancements:

• N/A

General Maintenance:

• Bug fixes and general maintenance

OS Support:

• Windows 10, 11
• Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2025

Please note that Windows 7 and Windows Server 2008 (R2) are not supported. On endpoints where these operating systems are in use, the Countercept agent will not be updated, and the previous sensor version (2024.2.31) will continue to run. New Countercept agent installations to these operating systems are now impossible.

The update is related to the Countercept Agent’s Ultralight Core. Ultralight Core provides low-level functionality such as file hash calculation as part of the agent’s reporting of endpoint activity.

Product Name: Countercept Agent for Windows – Ultralight Core

Version: 2.1.21067

Pilot Availability: 03/12/2025

General Availability: 11/12/2025

Predecessor: 2.1.20934

Release Purpose:

• General maintenance

Customer Action Required:

• N/A

Name Changes:

• No changes to file, process, or service names.

Files Updated:

• CapricornScanner.exe
• fshoster64.exe
• FsPisces.exe
• fsulgk.sys
• install.exe
• uninstall.exe

New Features and Enhancements:

• N/A

General Maintenance:

• General maintenance of functionality not utilized by Countercept.

OS Support:

• Windows 10, 11
• Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2025

The update is related to the Countercept Agent’s Security Cloud Core component. The Security Cloud Core component provides means for accessing WithSecure’s Security Cloud functionalities utilized by the agent’s detection components.

Product Name: Countercept Agent for Windows – Security Cloud Core

Version: 2.1.20961

Pilot Availability: 26/11/2025

General Availability: 04/12/2025

Predecessor: 2.1.20854

Release Purpose:

• General maintenance

Customer Action Required:

• N/A

Name Changes:

• No changes to file, process, or service names.

Files Updated:

• install.exe

New Features and Enhancements:

• N/A

General Maintenance:

• General maintenance of functionality not utilized by Countercept.

OS Support:

• Windows 10, 11
• Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2025

The update is related to the Countercept Agent’s Sensor component. The Sensor component gathers data to be analyzed in the WithSecure backend to identify any malicious activity. 

Product Name: Countercept Agent for Windows – Sensor Component

Version: 2025.3.54

Pilot Availability: 18/11/2025

General Availability: 02/12/2025

Predecessor: 2025.2.44

Release Purpose:

• New Features and Enhancements
• Generic maintenance

Customer Action Required:

• The Operating System should be Azure Code Signing (ACS) compliant to receive this update. See 
  
  https://community.withsecure.com/en/kb/articles/29714-changes-in-support-on-microsoft-windows-minimum-patch-level
  
  
      for more details.
  Any endpoints which are not ACS-compliant will continue to run the previous production version of the sensor (2023.1.75).

Name Changes:

• No changes to file, process, or service names.

Files Updated:

• fsatp.sys
• fsatpl.exe
• fsatpn.exe
• install.exe
• sensor_control.exe

New Features and Enhancements:

• New detections and detection improvements
• Improved process protection

General Maintenance:

• Bug fixes and dependency updates

OS Support:

• Windows 10, 11
• Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2025

Please note that Windows 7 and Windows Server 2008 (R2) are not supported. On endpoints where these operating systems are in use, the Countercept agent will not be updated, and the previous sensor version (2024.2.31) will continue to run. New Countercept agent installations to these operating systems are now impossible.

The update is related to the Countercept Agent’s Ultralight Core component. Ultralight Core provides low-level functionality such as file hash calculation as part of the agent’s reporting of endpoint activity.

Product Name: Countercept Agent for Windows – Ultralight Core

Version: 2.1.20934

Pilot Availability: 30/10/2025

General Availability: 06/11/2025

Predecessor: 2.1.20768

Release Purpose:

• General maintenance

Customer Action Required:

• The Operating System should be Azure Code Signing (ACS) compliant to receive this update. See 
  
  https://community.withsecure.com/en/kb/articles/29714-changes-in-support-on-microsoft-windows-minimum-patch-level
  
  
                 for more details.
  Any endpoints which are not ACS-compliant will continue to run the older version of the Ultralight Core (2.1.16183).

Name Changes:

No changes to file, process, or service names.

Files Updated:

• CapricornScanner.exe
• fshoster64.exe
• FsPisces.exe
• fsulgk.sys
• install.exe
• uninstall.exe

New Features and Enhancements:

• N/A

General Maintenance:

• General maintenance of functionality not utilized by Countercept.

OS Support:

• Windows 10, 11
• Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2025

This is a notification that the update to our Windows agent’s Ultralight Core planned for GA release tomorrow, 15th of October 2025, has been cancelled. A new release schedule will be communicated when we have identified and resolved the observed issues. We apologize for the delays related to this particular release, but we are committed to making sure that we release content with the highest possible quality.

The update is related to the Countercept Agent’s Security Cloud Core component. The Security Cloud Core component provides means for accessing WithSecure’s Security Cloud functionalities utilized by the agent’s detection components.

Product Name: Countercept Agent for Windows – Security Cloud Core

Version: 2.1.20854

Pilot Availability: 09/10/2025

General Availability: 16/10/2025

Predecessor: 2.1.20491

Release Purpose:

• General maintenance

Customer Action Required:

• N/A

Name Changes:

• No changes to file, process, or service names.

Files Updated:

• install.exe

New Features and Enhancements:

• N/A

General Maintenance:

• Updated the third-party curl library to the latest version.
• General maintenance of functionality not utilized by Countercept.

OS Support:

• Windows 10, 11
• Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2025

This is a notification that the update to our Windows agent’s Ultralight Core planned for GA release today, 8th of October 2025, has been postponed until Wednesday 15th of October for further investigations due issues observed in a small number of clients during Pilot phase. We apologize for the delays related to this particular release, but we are committed to making sure that we release content with the highest possible quality.

The update is related to the Countercept Agent’s Ultralight Core component. Ultralight Core provides low-level functionality such as file hash calculation as part of the agent’s reporting of endpoint activity.

Product Name: Countercept Agent for Windows – Ultralight Core

Version: 2.1.20768

Pilot Availability: 01/10/2025

General Availability: 08/10/2025

Predecessor: 2.1.20648

Release Purpose:

• General maintenance

Customer Action Required:

• The Operating System should be Azure Code Signing (ACS) compliant to receive this update. See 
  
  https://community.withsecure.com/en/kb/articles/29714-changes-in-support-on-microsoft-windows-minimum-patch-level
  
  
                for more details.
  Any endpoints which are not ACS-compliant will continue to run the older version of the Ultralight Core (2.1.16183).

Name Changes:

No changes to file, process, or service names.

Files Updated:

• CapricornScanner.exe
• fshoster64.exe
• FsPisces.exe
• install.exe
• uninstall.exe

New Features and Enhancements:

• N/A

General Maintenance:

• General maintenance of functionality not utilized by Countercept.

OS Support:

• Windows 10, 11
• Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2025