Netscaler 11.1, SecureWeb external HTTPS traffic not working

I’ve come across an issue after upgrading netscaler to & that external SSL traffic that is sent via HTTP proxy is failing with the following error message.

Cannot Open Page
The request timed out.

Netscaler is running, or firmware
SecureWeb version 10.4 (or above)
SecureWeb is configured to tunnel traffic to internal network with SecureBrowse method
Netscaler gateway has a traffic policy configured that sends external traffic to a HTTP proxy
HTTP proxy has authentication enabled

External HTTP sites can be accessed with no issues using SecureWeb
Accessing HTTPS sites fails immediately with the following error message being displayed:

Cannot Open Page
The request timed out.

Looking into the network trace on the netscaler we can see that the netscaler immediately resets the connection to proxy after successfully establishing a tunnel via the CONNECT method.

This issue is caused by a bug in the netscaler firwamre and is resolved by upgrading to netscaler