Forms using FileUpload or ImageUpload elements with a custom saveToFileMount configured stored uploaded files in the default storage folder 1:/user_upload/ instead of the configured destination. This could cause uploaded files to end up in a publicly accessible storage even though a restricted, non-public storage had been configured. Files stored this way are served directly, without the access checks applied to non-public storages. Forms that use the default value for saveToFileMount are not affected. This issue affects TYPO3 CMS versions 14.0.0-14.3.8.