Allow Trusted Locations on the network
This per-user registry value controls whether PowerPoint can use network locations as Trusted Locations.
since 0.9.8.11
Purpose
Show registry keys (1)
HKCU\software\policies\microsoft\office\16.0\powerpoint\security\trusted locations\allownetworklocations
This per-user registry value controls whether PowerPoint can use network locations as Trusted Locations.
The value is a REG_DWORD. A value of 1 permits Trusted Locations on network shares and other remote locations. A value of 0 blocks their use. PowerPoint then ignores network locations added by users as well as network locations defined through policy.
A network folder must also be defined as a Trusted Location. This value does not designate any location as trusted by itself.
Notes
Security
PowerPoint treats files opened from an effective Trusted Location as trusted. Among other protections, these files bypass file validation and File Block checks and do not open in Protected View or Microsoft Defender Application Guard. Active content such as VBA macros, ActiveX controls, add-ins, and external data connections can load without the security prompts or checks that would normally apply.
For a network-based Trusted Location, security therefore depends heavily on the share and file-system permissions. If an untrusted user can add or modify files in an allowed network folder, active content placed there can run with the privileges of the signed-in user.
Possible side effects
With a value of 0, existing network entries cease to function as Trusted Locations but are not removed from the list. Files in those locations become subject to PowerPoint's normal security checks. Active content might consequently be blocked, security warnings might appear, or files might open in a protected environment.
Notes
If the policy value is absent, this policy does not enforce a state. PowerPoint initially prevents users from adding network-based Trusted Locations, but users can enable the corresponding Trust Center option themselves unless another policy prevents it.
This setting applies only to PowerPoint in the current user's context. Policies for other Office applications, including similarly named values in their registry branches, are unaffected.
Microsoft documentation
Microsoft Learn: Trusted Locations for Office files