Full Disk Access
Full Disk Access is a security setting in macOS that determines which programs are allowed to read all files on the computer – even those that are normally protected. Without this permission, an app can only access a small portion of the file system.
Operating systems like macOS restrict which programs are allowed to read which files. Full Disk Access is a special permission an app receives when it is allowed to read absolutely all files on the storage – including mail, messages, browser data, and system files that are otherwise locked. Without this permission, an app only sees what the operating system explicitly grants it. The principle behind this is called a sandbox: by default, every app operates in a shielded area it cannot escape. Full Disk Access lifts this barrier.
Full Disk Access as a security line
This restriction exists because an open file system poses a significant risk. Malware that can read all files unhindered could capture and send out passwords, private photos, or bank documents. Apple therefore introduced Full Disk Access in 2018 with macOS Mojave, as a response to exactly such attacks.
The permission must be granted manually by a user. An app cannot silently switch it on for itself. This is intentional: anyone who never opens System Settings never grants this permission. In this way, Full Disk Access functions like a physical key that must be consciously handed over.
It is also important to understand what Full Disk Access does not guarantee: it is not encryption. It does not protect against someone with physical access to the hard drive reading out the data. It only regulates which running programs on one’s own Mac may open which folders.
Which app gets to see what
macOS divides the file system into protection levels. An app may read its own Documents folder after a one-time prompt. Certain areas – such as the mail storage under ~/Library/Mail or the Messages database – are fundamentally locked. Only apps with Full Disk Access can access them.
Technically, macOS enforces this through an internal protection mechanism called TCC, short for Transparency, Consent and Control. TCC maintains a list of all granted permissions. If an app attempts to access a locked folder, TCC prompts the user – or blocks access outright if Full Disk Access was never granted. The list of permissions can be viewed and revoked at any time under System Settings → Privacy & Security → Full Disk Access.
There are limits here too. Apple’s own system apps are exempt from TCC. And anyone logged in as an administrator on the Mac who deliberately manipulates TCC can bypass these barriers. Security researchers have repeatedly demonstrated such attacks.
Where Full Disk Access shows up in everyday life
Most users encounter the term when installing backup software, an antivirus program, or an AI assistant. These programs need to see all files in order to do their job. Without Full Disk Access, a backup tool simply cannot back up certain folders – and will then warn with an error message.
Some AI applications ask for it as well. Apple Intelligence, Apple’s own AI system for Mac, accesses mail and messages to deliver context-aware answers. This requires the permission. The same applies to external AI tools that search the computer for documents in order to answer questions.
In the security industry, Full Disk Access is considered a sensitive right that should be granted sparingly. An app that requests it without an obvious reason is a warning sign. Some well-known data leaks can be traced back to users granting the permission thoughtlessly – for instance, by quickly clicking through an installation dialog.