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: 2.1.22462

Pilot Availability: 17/09/2026

General Availability: 24/09/2026

Predecessor: 2.1.22416

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

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: 2026.3.49

Pilot Availability: 14/09/2026

General Availability: 21/09/2026

Predecessor: 2026.3.43

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.

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:

• Security fixes and bug fixes

OS Support:

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

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: 2.1.22416

Pilot Availability: 10/09/2026

General Availability: 17/09/2026

Predecessor: 2.1.22029

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

New Features and Enhancements:

• N/A

General Maintenance:

• Vulnerability fixes and bug fixes

OS Support:

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

The update is related to the response component of the Countercept Agent, which enables the Detection and Response Team to retrieve artefacts for analysis or contain any identified threats within the environment.

Product Name: Countercept Agent for Windows – Response component

Version:

• 1.0.617.421

Pilot Availability: 01/09/2026

General Availability: 08/09/2026

Predecessor:

• 1.0.530.395

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:

• Bug fixes

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: 2026.3.43

Pilot Availability: 27/07/2026

General Availability: 10/08/2026

Predecessor: 2026.2.37

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.

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
• Added support for Microsoft’s Driver Package Isolation

General Maintenance:

• Bug fixes, security fixes and dependency updates

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: 2.1.22151

Pilot Availability: 14/07/2026

General Availability: 21/07/2026

Predecessor: 2.1.21903

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:

• Updates to third-party libraries and vulnerability fixes.

OS Support:

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

The update is related to the Countercept Agent’s Ultralight Updater. 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 Updater

Version: 2.1.22067

Pilot Availability: 29/06/2026

General Availability: 07/07/2026

Predecessor: 2.1.20910

Release Purpose:

• General maintenance

Customer Action Required:

• N/A

Name Changes:

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

Files Updated:

• install.exe 
• ulu.exe 
• ulu_handler.exe 
• ulu_handler_ns.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

Update to previous release schedule

The update to our Windows agent’s Response Engine (RE) and Common Response Actions Module (CRAM) planned for GA release on 15th of June 2026, has been postponed until Wednesday 17th of June 2026.

The update is related to the Countercept Agent’s Response Engine (RE) and Common Response Actions Module (CRAM) components. The Response Engine and Common Response Actions Module components of the Countercept Agent enable the Detection and Response Team to retrieve artefacts for analysis or contain any identified threats within the environment. 

Product Name: Countercept Agent for Windows – CRAM and RE

Version:

• Response Engine 3.3.5
• CRAM 3.50.42

Pilot Availability: 08/06/2026

General Availability: 17/06/2026

Predecessor:

• Response Engine 3.3.3
• CRAM 3.30.35

Release Purpose:

• General maintenance

Customer Action Required:

• N/A

Name Changes:

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

Files Updated:

• ffind.exe
• fls.exe
• fscram-response.exe
• icat.exe
• ifind.exe
• install.exe
• mmcat.exe
• mmls.exe
• mmstat.exe
• verify.exe
• winpmem_1.6.2.exe
• winpmem_2.1.post4.exe
• winpmem_mini_x64_rc2.exe

New Features and Enhancements:

• N/A

General Maintenance:

• Updates to third-party libraries and vulnerability fixes

OS Support:

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

Update to previous release schedule and version

Windows agent’s Ultralight Core release planned for General Available release on Monday, 8th of June 2026, has been cancelled due to an issue found during the 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. 

A new version of Ultralight Core (2.1.22029) that fixes the issue found will be delivered to Pilot group endpoints on Monday, the 8th of June 2026, with a General Availability (GA) release on Monday, the 15th of June 2026.

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: 2.1.21987 / 2.1.22029

Pilot Availability: 01/06/2026 / 08/06/2026

General Availability: 08/06/2026 / 15/06/2026

Predecessor: 2.1.21833

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:

• fshoster64.exe
• FsPisces.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 FSBG components. The FSBG component is responsible for the core functionality (e.g. settings management and updates) of the Countercept Agent and does not affect the components responsible for telemetry collection or response.

Product Name: Countercept Agent for Linux – FSBG

Version: 1.0.931

Pilot Availability: 21/05/2026

General Availability: 01/06/2026

Predecessor: 1.0.930

Release Purpose:

• Generic Maintenance

Customer Action Required:

• N/A

Name Changes:

• Several auxiliary files have been added in this release.
• No changes to process, or service names.

Files Updated:

• Most files are updated with this release.

New Features and Enhancements:

• N/A

Generic Maintenance:

• Changes to the functionality not utilized by Countercept.
• Minor bug fixes and improvements.

OS Support:

• AMD64
  • AlmaLinux 8.4 – 9.x
  • Amazon Linux 2
  • CentOS 7, 8
  • Debian 10, 11, 12
  • Oracle Linux 7, 8, 9 (RHCK and UEK)
  • RHEL 7, 8, 9
  • Rocky Linux 8, 9
  • SUSE Linux Enterprise Server 12 SP3 – SP5
  • SUSE Linux Enterprise Server 15
  • Ubuntu 18.04, 20.04, 22.04, 24.04
• ARMv8/AArch64
  • Debian 11, 12
  • Rocky 9
  • Ubuntu 22.04, 24.04