Encrypted messages from users of Apple Mail on the macOS operating system can in some cases be viewed encrypted. Apple may have known of the leak for months, writes The Verge .

The affected group is relatively small. It only concerns Apple Mail users on macOS machines that do not use other apps to encrypt the entire system, such as FileVault. Researcher Bob Gendler found a text file with the unencrypted content of seemingly encrypted emails in the macOS database files.

The leak was in the four most recent versions of Apple's operating system. It is close by forbidding Siri through the institutions to learn from Apple Mail. This is done via the macOS Siri settings menu.

Gendler warns that previously sent encrypted e-mails can still be viewed unless the underlying file, snippets.db, is deleted. Turning FileVault on can also solve the problem.

Apple reports to the Engadget website that it is planning to close the leak soon.