ArcadeDB before 26.8.1 (affected versions <= 26.7.3) contains a missing authorization vulnerability in the DELETE FUNCTION SQL statement. DeleteFunctionStatement.executeSimple unregisters and persists deletion of a server-side function without any checkPermissionsOnDatabase (UPDATE_SCHEMA) check. Any user with database access can execute DELETE FUNCTION via the command API (POST /api/v1/command/{db}) to permanently remove any registered server-side function, including security-relevant logic, impacting integrity and availability.