While SP4 is the final update, some legacy systems still require SP3 Express .

You can still find the installer for SQL Server 2012 Service Pack 4 (SP4) Express on the Microsoft Download Center.

These paid editions are not available for general public download. Historically, users accessed these through a Visual Studio Subscription (formerly MSDN) or specific enterprise licensing agreements.

For developers needing connectivity components, the SQL Server 2012 Native Client and Feature Pack remain available for compatibility with older applications. Critical Support and Security Warning Microsoft® SQL Server® 2012 Service Pack 3 (SP3) Express

Understanding SQL Server 2012 Download Options and Support Status

sql server 2012 download