Bug in iOS can break iPhone Wi-Fi using rogue hotspot name

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A bug has been discovered in iOS that can disable an iPhone's ability to connect to Wi-Fi hotspots, if it attempts to initially connect to a hotspot with a specific name that breaks the function.

Security researcher Carl Schou gave a personal Wi-Fi hotspot a name of "%p%s%s%s%s%n." On trying to connect to the hotspot, Schou discovered the iPhone simply couldn't connect to it at all, and later discovered that it disabled Wi-Fi connectivity completely on the device.

Attempts to connect to other hotspots failed, with the issue continuing to mainifest after changing the hotspot's SSID and rebooting the iPhone, according to BleepingComputer. The issue was also confirmed by others testing out the same SSID name separately.

Tests also point to it being a problem just with iPhones, as Android devices appear to connect to the unusually-named access point without issue.

Other researchers examining the phenomena believe it is an issue with input parsing, in that the percentage sign at the start may be misinterpreted by iOS as a string-format specifier, in that characters following may be a variable or a command rather than plain text.

To fix the problem on affected iPhones, users have to reset their iOS network settings.

How to reset network settings in iOS

  • Open Settings
  • Select General then Reset
  • Select Reset Network Settings
  • Confirm the request.
  • Once the iPhone has restarted, set up your Wi-Fi as normal.

The discovery is reminiscent of text messages that contained strings and special characters that could cause problems for iPhones and iPads. For example, April's "text bomb" forced iPhones to crash if a flag emoji and a specific Sindhi language character were viewed in an incoming notification.

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