diff --git a/src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsParser.cs b/src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsParser.cs
index 4366b4665a..c7d170f442 100644
--- a/src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsParser.cs
+++ b/src/Microsoft.Data.SqlClient/src/Microsoft/Data/SqlClient/TdsParser.cs
@@ -25,6 +25,8 @@ internal void ProcessSSPI(int receivedLength)
                 throw SQL.SynchronousCallMayNotPend();
             }
 
+            receivedBuff.AsSpan(receivedLength, receivedBuff.Length - receivedLength).Clear();
+
             // allocate send buffer and initialize length
             byte[] rentedSendBuff = ArrayPool<byte>.Shared.Rent((int)_authenticationProvider!.MaxSSPILength);
             byte[] sendBuff = rentedSendBuff; // need to track these separately in case someone updates the ref parameter