With the release of Microsoft’s April 2026 cumulative security update for Windows Server, it has been confirmed that this update includes mandatory security enhancements to the user authentication protocol, directly impacting Forcepoint Proxy’s integrated Windows authentication functionality.

This update will cause users to experience continuous authentication pop-ups and authentication failures.

To avoid affecting the normal internet access and network security of all employees, all maintenance teams must pay attention to and cooperate with the recommended measures.

Core Affected Scope: The following April security updates will trigger the proxy authentication issue:
Windows Server 2019: KB5082123
Windows Server 2022: KB5082142
Windows Server 2025: KB5082063

Recommended Countermeasures:

To ensure the stability of the enterprise network and authentication, all maintenance teams should take the following actions:

Suspend Installation: Immediately suspend the installation and distribution of the aforementioned April 2026 Windows security update. If the above updates are already installed in your environment, it is recommended to evaluate and remove them as soon as possible to avoid potential anomalies.

Observation and Waiting: The current version will continue to operate. We will notify you to restore updates once Forcepoint provides official operating instructions and verifies their correctness.

Thank you for your cooperation.