Just a week after releasing iOS 18.3.2 to the public, Apple has now stopped signing iOS 18.3.1. For iPhone and iPad users, this means that they can no longer downgrade to this version of the software if their device is already running a newer version.Apple blocks downgrade from iOS 18.3.2 to iOS 18.3.1iOS 18.3.2 was released on March 11 with an important security patch. According to Apple, the update resolves an exploit in WebKit that allowed malicious web content to break the sandbox. The company says its aware that this exploit was actively used in a extremely sophisticated attack against specific targeted individuals.As for iOS 18.3.1, the update was released on February 10, also with a specific security patch. In this case, iOS 18.3.1 fixed an exploit that allowed attackers with physical access to an iPhone or iPad to disable USB Restricted Mode on a locked device. USB Restricted Mode is a feature that asks for theiPhoneoriPadspassword to allow it to be connected to a computer or other device via USB.Its important to keep your devices software up to date to protect yourself against hackers and other attacks. Thats why Apple stops signing old versions of iOS. Of course, this ends up affecting users experiencing bugs with the latest version of iOS, since they cant go back to the previous version.Right now, the only possible downgrade is from iOS 18.4 beta to iOS 18.3.2. If you have a compatibleiPhoneoriPad, make sure you update iOS by going to Settings > General > Software Update.Gadgets I recommend:Add 9to5Mac to your Google News feed. FTC: We use income earning auto affiliate links. More.Youre reading 9to5Mac experts who break news about Apple and its surrounding ecosystem, day after day. Be sure to check out our homepage for all the latest news, and follow 9to5Mac on Twitter, Facebook, and LinkedIn to stay in the loop. Dont know where to start? Check out our exclusive stories, reviews, how-tos, and subscribe to our YouTube channel