Site isolation for every site must be enabled.

Description

<VulnDiscussion>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.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>