Apple today released new iOS and iPadOS 12.5.4 updates, with the new software aimed at older devices that are unable to run the iOS 14 update that's available on modern devices.
The iOS and iPadOS 12.5.4 updates can be downloaded for free and the software is available on all eligible devices over-the-air in the Settings app. To access the new software, go to Settings > General > Software Update.
According to Apple's release notes, iOS 12.5.4 introduces important security updates and is recommended for all users. Apple often releases security updates for older devices that are no longer able to get the current version of iOS in order to keep users protected from malware and other security vulnerabilities.
Apple's security support document says that the update addresses three vulnerabilities that could lead to arbitrary code execution. Two of them that affected WebKit may have been actively exploited. One of these vulnerabilities was fixed in iOS 14.6, and the other two are likely to be addressed in iOS 14.7.
Source: Macrumors