Apple has confirmed it will fix a privacy issue in which Siri can read aloud hidden lock screen notifications from many apps on iPhones.
In a statement provided to MacRumors, Apple said "we are aware of the issue and it will be addressed in an upcoming software update." It's quite possible the fix will be included in iOS 11.3, which remains in beta testing, but Apple may elect to address the problem with a minor update such as iOS 11.2.7.
As reported by Brazilian website MacMagazine earlier this week, users can simply ask Siri to "read my notifications" and the assistant will read aloud the contents of notifications, including ones that are hidden, from a wide selection of apps.
Siri's behavior becomes a privacy issue because it can read aloud messages and emails from third-party apps such as Facebook Messenger, WhatsApp, and Gmail, even if an iPhone is locked and notifications are hidden. This violates the trust of users who expect that their notifications cannot be read by others.
MacRumors has reproduced this issue on an iPhone X running both iOS 11.2.6 and the latest iOS 11.3 beta, but we can confirm that it does not affect iMessage. However, the issue did partially affect Apple's stock Mail app, as Siri was able to read the subject line of an email we sent as part of our testing.
Lock screen notifications are hidden by default on iPhone X, meaning the contents of notifications are concealed until a user authenticates with Face ID. The setting isn't turned on by default on other iPhones, but it can be enabled in Settings > Notifications > Show Previews, which presents three options:
Always: Lock screen notifications are fully visible
When Unlocked: Lock screen notifications remain hidden until a user authenticates with Face ID, Touch ID, or a passcode
Never: Lock screen notifications are always hidden
There are two workarounds that users can implement until the fix is released to prevent Siri from reading aloud notifications from the lock screen:
Turn off lock screen notifications for sensitive apps: Settings > Notifications, select an app, and toggle off Show on Lock Screen
Fully disable Siri whenever the iPhone is locked: Settings > Siri & Search > Allow Siri When Locked
Source: macrumors