Shortly after the discovery of the Microsoft backdoor to their webserver, an Internet security company discovered a backdoor in an administration tool specific to a popular open source Linux distribution, Red Hat. The administration tool, codenamed Pirhana, used to configure, and grant unhindered access to the Red Hat Linux operating system, had a backdoor.
The password for this software was a simple ``Q''. Before the news even hit the websites, the company Red Hat, had released a source code patch for the software to fix the problem. They had confirmed and acknowledged it's existence. The response was timely, and efficiently executed. They even offered a reason for the existence of the backdoor: to test the software before it was released. Red Hat also stated that this backdoor was immediately closed when the system administrator would remove the sample user configuration files from the system. However, this note, was buried in the documentation, and rarely the system administrators read to that depth.
This Pirhana tool, had been out no more than two weeks to a month before the security hole was discovered. Furthermore, the Internet security company discovered this backdoor by closely scrutinising the source code. Surely, had the software been closed source, it would have taken much longer for the backdoor to be discovered.