Dispose IDisposable instances (#15810)

src/Umbraco.Core/Security/LegacyPasswordSecurity.cs

@@ -16,8 +16,11 @@ public class LegacyPasswordSecurity
     public static string GenerateSalt()
     {
         var numArray = new byte[16];
-        new RNGCryptoServiceProvider().GetBytes(numArray);
-        return Convert.ToBase64String(numArray);
+        using (var rng = new RNGCryptoServiceProvider())
+        {
+            rng.GetBytes(numArray);
+            return Convert.ToBase64String(numArray);
+        }
     }
 
     // TODO: Remove v11
@@ -86,7 +89,7 @@ public class LegacyPasswordSecurity
     /// </summary>
     public bool VerifyLegacyHashedPassword(string password, string dbPassword)
     {
-        var hashAlgorithm = new HMACSHA1
+        using var hashAlgorithm = new HMACSHA1
         {
             // the legacy salt was actually the password :(
             Key = Encoding.Unicode.GetBytes(password),

src/Umbraco.Core/Security/PasswordGenerator.cs

@@ -98,7 +98,10 @@ public class PasswordGenerator
                 var data = new byte[length];
                 var chArray = new char[length];
                 var num1 = 0;
-                new RNGCryptoServiceProvider().GetBytes(data);
+                using (var rng = new RNGCryptoServiceProvider())
+                {
+                    rng.GetBytes(data);
+                }
 
                 for (var index = 0; index < length; ++index)
                 {