Brazilian site MacMagazine originally reported the bug earlier this week, noting that asking Siri to read notifications out loud inadvertently includes those that are hidden (i.e. need authentication before they're shared). SMS and iMessages are still kept private, The Verge reported, but Siri reads out hidden messages from third-party apps like Facebook Messenger, WhatsApp and Gmail. Engadget tested this yesterday, and the bug performed as described.

Until an update fixes the issue, there are two currently viable workarounds that Apple recommends:

— Turn off lock screen notifications for sensitive apps (Go to the app in Settings > Notifications > Show on Lock Screen)

— Disable Siri whenever the device is locked (Settings > Siri & Search > Allow Siri When Locked)