Do not allow drive redirection
This computer policy controls whether drives from a client device are made available in Remote Desktop Services sessions hosted by the computer.
since 0.9.8.11
Purpose
Show registry keys (1)
HKLM\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services\fDisableCdm
This computer policy controls whether drives from a client device are made available in Remote Desktop Services sessions hosted by the computer. The fDisableCdm registry value is a REG_DWORD; a value of 1 prevents client drive redirection.
Without this restriction, supported Remote Desktop clients can redirect resources such as fixed drives, removable storage, and connected network drives into the remote session. The redirected resources appear as drives or network resources and can be used by applications running in that session.
Notes
Additional effects
Blocking drive redirection also prevents files from being transferred between the local device and the remote session through the clipboard. The setting does not by itself block other supported clipboard content, such as text or images.
Security
The policy limits access by remote-session users and processes to redirected drives on the client device. This restricts a transfer path through which local files could otherwise be read or modified from the remote session, or files could be moved between the client and the session.
It does not remove access to drives belonging to the session host or disable other forms of device and resource redirection. Those capabilities are governed by separate policies and permissions.
Possible side effects
Applications in the remote session can no longer access drives on the client device directly. Workflows that open or save files on local or redirected network drives, or transfer files through the clipboard, therefore become unavailable. Files may need to be supplied through another permitted storage or transfer mechanism.
Notes
The setting applies to the computer providing the remote session. Azure Virtual Desktop and similar services can impose additional redirection controls. Where multiple controls apply, the most restrictive effective setting determines the resulting behavior.
Microsoft documentation
Microsoft Learn: RemoteDesktopServices Policy CSP – DoNotAllowDriveRedirection
Microsoft Learn: Configure fixed, removable, and network drive redirection over RDP