iOS Bug Causes Specific Network Name to Disable Wi-Fi on iPhones

Security researcher Carl Schou found that after joining a Wi-Fi network with the name "%p%s%s%s%s%n" his ‌iPhone‌'s Wi-Fi functionality was left "permanently disabled."

Changing a hotspot's SSID did nothing to correct the problem, with even a reboot failing to make a difference, according to BleepingComputer.

Other users who were able to replicate the issue have suggested the bug could be related to the initial use in the network name of the percentage sign, which leads to an input parsing issue whereby iOS mistakenly interprets the letters following the "%" as a string-format specifier.

After joining my personal WiFi with the SSID “%p%s%s%s%s%n”, my ‌iPhone‌ permanently disabled it’s WiFi functionality. Neither rebooting nor changing SSID fixes it :~) pic.twitter.com/2eue90JFu3 — Carl Schou (@vm_call) June 18, 2021 In C and C-style languages, string format specifiers have a special meaning and are parsed by the language compiler as a variable name or a command instead of standard text.

After joining my personal WiFi with the SSID “%p%s%s%s%s%n”, my ‌iPhone‌ permanently disabled it’s WiFi functionality. Neither rebooting nor changing SSID fixes it :~) pic.twitter.com/2eue90JFu3 — Carl Schou (@vm_call) June 18, 2021

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