clientStream were undisposed.

---------------------------
//1st clientStream
var clientStream = new CustomBufferedStream(clientConnection.GetStream(), BufferPool, BufferSize);
sslStream = new SslStream(clientStream, false); //false => do not dispose 1st ClientStream
//2nd clientStream
clientStream = new CustomBufferedStream(sslStream, BufferPool, BufferSize);

...

sslStream?.Dispose(); // dispose sslStream but not 1st ClientStream
clientStream.Dispose(); // dispose 2nd ClientStream, sslStream (already disposed)
//here 1st clientStream is not disposed
---------------------------

Author: StephaneGraziano

src/Titanium.Web.Proxy/ExplicitClientHandler.cs

@@ -182,7 +182,7 @@ await clientStreamWriter.WriteResponseAsync(connectArgs.HttpClient.Response,
                         X509Certificate2 certificate = null;
                         try
                         {
-                            sslStream = new SslStream(clientStream, true);
+                            sslStream = new SslStream(clientStream, false);
 
                             string certName = HttpHelper.GetWildCardDomainName(connectHostname);
                             certificate = endPoint.GenericCertificate ??

src/Titanium.Web.Proxy/TransparentClientHandler.cs

@@ -67,7 +67,7 @@ private async Task handleClient(TransparentProxyEndPoint endPoint, TcpClientConn
                         X509Certificate2 certificate = null;
                         try
                         {
-                            sslStream = new SslStream(clientStream, true);
+                            sslStream = new SslStream(clientStream, false);
 
                             string certName = HttpHelper.GetWildCardDomainName(httpsHostName);
                             certificate = endPoint.GenericCertificate ??