"Unauthorised access" refers to the act of gaining entry or using something without proper permission or authority. It is like entering a place or using information, devices, or systems without being allowed to do so. Full definition
They can also provide a means of preventing unauthorised access to playgrounds during school hours. (educationmattersmag.com.au)
Confidential material should remain protected from unauthorised access from the point of collection to complete destruction and should only be collected by uniformed and suitably trained staff carrying photographic identification. (educationbusinessuk.net)
There are all sorts of possibilities, from accidental large - scale disclosure (the HMRC scenario) to isolated instances of unauthorised access by individual employees. (newlawjournal.co.uk)