iOS 16 Bug Locking Users Out of Mail App With a Single Email

Discovered first by VPN Tracker service Equinux, an iOS 16 bug is causing the Mail app to crash instantly when a single email that contains some weird text in the “from” field is received, 9to5Mac is reporting.

Ios bug

This flaw in iOS 16, which is resulting in iPhone users completely locking out of the Mail app, was identified by Equinux when analyzing spam emails. “We started seeing iOS mail problems for multiple people on our team: Mail was crashing immediately on launch,” they said.

The “From” field in an inbound email usually looks like this:

  • From: sender@example.com.

However, the maliciously crafted email has a “From” field that looks like this instead:

  • From: “”@example.com.

According to Equinux, “anyone can send any iOS 16 user an email that can lock them out of their inbox.” They have also created a from field on their website that you can use to test the bug, which they are referring to as “Mailjack.”

Mailjack can impact the Mail app on any device running iOS 16 (the stable release), iOS 16.0.1 on the iPhone 14, and the latest iPadOS 16 betas, but there are some caveats. Some mail services, including Gmail, Outlook, and Hotmail rewrite inbound emails to prevent things like this from happening.

Additionally, Gmail and Yahoo block these maliciously crafted emails entirely.

There are a number of IMAP mail services that “do not correct or rewrite inbound mails,” such as iCloud, although the email may get marked as spam so you’ll need to check your spam folder.

Apple has not yet issued any comment regarding the matter, but a fix for the bug should be coming soon.

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