Apparently, Salesforce has released a patch that implicated “Modify all” to be enabled for every single profile in some orgs. This includes standard profiles and custom as well. Yes, even standard profiles!
Very serious stuff. Please make sure you weren’t affected.
Link to Salesforce Trust: https://status.salesforce.com/products/all
Please make sure you follow this discussion:
Guidance on how admins can manually restore user permissions can be found in this Known Issue article
You can easily check all of your profiles by clicking on “Your Name” > Developer Console > Query Editor, and using the following query:
SELECT Profile.Name, PermissionSet.Label FROM PermissionSet WHERE PermissionsModifyAllData = true
If you see any unexpected profiles there, you can try copying the profiles back from a Sandbox, if you have one available. Keep in mind that Modify All Data will also enable a ton of other object and system permissions, so simply unchecking the box is not sufficient to undo the damage that would be caused.