Sсhou said that if you create a Wi-Fi network and give it a name consisting of % characters and certain text characters, then the iPhone will not be able to connect to such a network. Moreover, when you try to create a connection on the device, the ability to select Wi-Fi networks will stop working. In this case, the owner of the device will only be able to use cellular communication.
The enthusiast who revealed the vulnerability also noticed that after renaming the SSID (Service Set Identifier) of the network, the phone still cannot connect to it. A popular way to fix such breakdowns on Apple smartphones — a reboot – does not help. Later it turned out that you can solve the problem by completely resetting the network settings in the device.
Users who unsubscribed in the comments under the post of Carl Schou suggested that the failure is due to an unusual SSID of the network. It is believed that the “%” sign leads to a problem of parsing input data when iOS mistakenly interprets this character as a special specifier.