On 14 February 2023, Microsoft released updates for all supported versions of SQL Server in the form of a General Distribution Release (GDR). A GDR is an out-of-band update that usually includes bug fixes and/or security patches. You can find out more about each release from aka.ms/sqlbuilds.
In this case, the GDR fixes a remote code execution (RCE) flaw, which is serious enough that they’ve released updates for all versions on the same day.
If you have Windows Updates enabled for Microsoft products and you have a supported version of SQL Server installed, you will already have seen this update. For the rest of you, including Linux and BDC customers, you will need to acquire the GDR through your usual update mechanism.
Patch your systems today. If you can’t do that, start planning today for patching them as soon as possible.
(Full disclosure: I work for Microsoft on the Database Docs team.)