In MISP before 2.4.187, __uploadLogo in app/Controller/OrganisationsController.php does not properly check for a valid logo upload.
The PHP application uses an old method for processing uploaded files by referencing the four global variables that are set for each file (e.g. $varname, $varname_size, $varname_name, $varname_type). These variables could be overwritten by attackers, causing the application to process unauthorized files.