KB5062557: This update includes a security hardening change to the Microsoft RPC Netlogon protocol.

July 8, 2025—KB5062557 (OS Build 17763.7558)

Summary
This security update includes fixes and quality improvements that were a part of the following update:

• June 10, 2025—KB5060531 (OS Build 17763.7434)

The following is a summary of the issues that this update addresses when you install this update. The bold text within the brackets indicates the item or area of the change we are documenting.

• [Network Security and Containers] Fixed: An issue in the CharNextW function which caused incorrect character rendering for GB18030-2022 compliance. The function has been deprecated and replaced with a modern ICU-based solution to ensure proper handling of GB18030-2022 requirements.
• [DHCP Server (known issue] Fixed: An issue in which the DHCP Server service might intermittently stop responding and affects IP renewal for clients.
• [Microsoft RPC Netlogon protocol] This update includes a security hardening change to the Microsoft RPC Netlogon protocol. This change improves security by tightening access checks for a set of remote procedure call (RPC) requests. After this update is installed, Active Directory domain controllers will no longer allow anonymous clients to invoke some RPC requests through the Netlogon RPC server. These requests are typically related to domain controller location. Certain file and print service software can be affected, including Samba. If your organization uses Samba, please refer to the Samba release notes. ​​​​​​​
• [Stability issue] Fixed: This update addresses an issue observed in rare cases after installing the May 2025 security update and subsequent updates causing devices to experience stability issues. Some devices became unresponsive and stopped responding in specific scenarios.