Apple has released iOS 16.1.1, iPadOS 16.1.1, and macOS Ventura 13.0.1 to close a pair of severe security vulnerabilities in libxml2 (a software library for parsing XML documents). Both allow a remote user to “cause unexpected app termination or arbitrary code execution.” Needless to say, it’s seriously problematic when a remote user could do such things. The saving grace is that the vulnerabilities were discovered by Google Project Zero and aren’t being exploited in the wild.
You can update to iOS 16.1.1 and iPadOS 16.1.1 in Settings > General > Software Update and update to macOS 13.0.1 in System Settings > General > Software Update. If your devices are running 16, iPadOS 16, or Ventura, you should update as soon as possible to fix these security issues. Apple hasn’t released security updates for its older but still supported operating systems; we don’t know if they’re immune or if those updates are coming soon.