Information
This policy settings controls whether the SMB client will use remote mailslots over Multiple UNC Provider (MUP). The remote mailslots protocol is an old, simple, unreliable, and insecure inter-process communication method.
The recommended state for this setting is: Disabled.
Remote mailslots is a legacy protocol that uses SMBv1 to function. This protocol is linked to known vulnerabilities, such as denial-of-service, buffer overflow, and remote code execution attacks.
Solution
To establish the recommended configuration via GP, set the following UI path to Disabled :
Computer Configuration\Policies\Administrative Templates\Network\Lanman Workstation\Enable remote mailslots
Note: A reboot is required after the setting is applied.
Note #2: This Group Policy path may not exist by default. It is provided by the Group Policy template LanmanWorkstation.admx/adml that is included with the Microsoft Windows 11 Release 24H2 Administrative Templates (or newer).
Impact:
If the remote mailslots feature was in operation, it will no longer function.
Warning: This setting may interfere with Windows Clustering.