TL;DR
- According to a researcher, a newly discovered iOS bug can disable an iPhone’s Wi-Fi connectivity.
- Connecting to a specific Wi-Fi network with “%” symbols seemingly causes the issue.
- The only known remedy is resetting the device’s saved network settings.
If you own an iPhone and don’t want to crash your device’s Wi-Fi functionality, you might want to double-check a network’s name before joining it. A security researcher has seemingly discovered an iOS bug that can disable an iPhone’s Wi-Fi capabilities.
Carl Schou, the researcher in question, found that an iPhone’s Wi-Fi connectivity is left “permanently disabled” by connecting to a network titled “%p%s%s%s%s%n.” According to BleepingComputer, Schou tested this theory on an iPhone XS running iOS 14.4.2. Notably, the publication, other researchers, and users in his Twitter thread have corroborated his findings. Notably, Android doesn’t seem affected by this issue.
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
Schou notes that rebooting the device doesn’t fix the issue. Changing the Wi-Fi network’s name doesn’t remedy the problem, either. Connecting to another network isn’t possible either, as this bug seemingly breaks the Wi-Fi settings page.
So what causes the issue? It’s believed a format string bug is the root cause. iOS seemingly interprets the letters following the “%” as commands or variables and not an actual Wi-Fi SSID.
How to fix the iPhone Wi-Fi bug
As easy as it is to get into this mess, there’s an equally easy way out. Heading to Settings > General > Reset > Reset Network Settings on your iPhone will clear the Wi-Fi name from the device’s logs. You will need to re-enter any safe Wi-Fi networks and other network information, though.
Although it’s a temporary annoyance, the bug doesn’t seem to be a security flaw and probably isn’t exploitable by malicious actors. That said, it would be a cruel trick to play on iOS users who are none the wiser.
