SilverStripe 2.3.x before 2.3.12 and 2.4.x before 2.4.6 allows remote authenticated users with the EDIT_PERMISSIONS permission to gain administrator privileges via a TreeMultiselectField that includes admin groups when adding a user to the selected groups.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.005
EPSS Ranking 64.7%