Site isolation for every site must be enabled.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-235760	SRG-APP-000141	EDGE-00-000047	SV-235760r960963_rule	2024-09-13	2

Description
The "SitePerProcess" policy can be used to prevent users from opting out of the default behavior of isolating all sites. The "IsolateOrigins" policy can be used to isolate additional, finer-grained origins. Enabling this policy prevents users from opting out of the default behavior where each site runs in its own process. If this policy is not disabled or configured, a user can opt out of site isolation (e.g., by using "Disable site isolation" entry in edge://flags.) Disabling the policy or not configuring the policy does not turn off Site Isolation.

Description

The "SitePerProcess" policy can be used to prevent users from opting out of the default behavior of isolating all sites. The "IsolateOrigins" policy can be used to isolate additional, finer-grained origins. Enabling this policy prevents users from opting out of the default behavior where each site runs in its own process. If this policy is not disabled or configured, a user can opt out of site isolation (e.g., by using "Disable site isolation" entry in edge://flags.) Disabling the policy or not configuring the policy does not turn off Site Isolation.

ℹ️ Check
The policy value for "Computer Configuration/Administrative Templates/Microsoft Edge/Enable site isolation for every site" must be set to "enabled". Use the Windows Registry Editor to navigate to the following key: HKLM\SOFTWARE\Policies\Microsoft\Edge If the value for "SitePerProcess" is not set to "REG_DWORD = 1", this is a finding.

✔️ Fix
Set the policy value for "Computer Configuration/Administrative Templates/Microsoft Edge/Enable site isolation for every site" to "enabled".