When you scan the area for WiFi networks to join, many names popup. These names are usually chosen by the owners of the network so sometimes you might come across some that are weird or funny. However, if you do come across a WiFi network that has the name “%p%s%s%s%s%n”, do not join it.
This is because according to security researcher Carl Schou, there seems to be a weird bug with iOS that just can’t seem to handle this particular WiFi name. What happens when you do join it is that it leads to your iPhone’s WiFi being permanently disabled. Schou also claims that changing the hotspot’s SSID or rebooting his phone made a difference.
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
The only way to get this fixed is to reset your iPhone’s network settings, which is thankfully pretty easy and less destructive compared to resetting your phone. You can see the video above from Schou that shows that when he tries to re-enable WiFi, it just keeps turning it back off. At the moment it is unclear why this is happening, but some speculate that the use of “%” could be the issue.
This is because in some programming languages, “%” is used as a string-format specifier, and that when iOS sees it, they might be trying to parse it which led to this issue. Oddly enough Android seems to be unaffected by it so for now it looks like it’s an iPhone thing. It’s not a phone breaking bug but hopefully Apple will issue a fix for it soon.