If you are using SQL Server 2005, following two are very important security updates not to be missed.
Security Update for SQL Server 2005 Service Pack 2 (KB948108)
A security issue has been identified in the SQL Server 2005 Service Pack 2 that could allow an attacker to compromise your system and gain control over it.
Security Update for SQL Server 2005 Service Pack 2 (KB948109)
A security issue has been identified in the SQL Server 2005 Service Pack 2 that could allow an attacker to compromise your system and gain control over it.
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