[ionised]

They collaborated with the NSA to develop an exploit in the SSL implementation used in Outlook.com.

From the Snowden documents;

July 31, 2012

Microsoft (MS) began encrypting web-based chat with the introduction of the new outlook.com service. This new Secure Socket Layer (SSL) encryption effectively cut off collection of the new service for FAA 702 and likely 12333 (to some degree) for the Intelligence Community (IC). MS, working with the FBI, developed a surveillance capability to deal with the new SSL. These solutions were successfully tested and went live 12 Dec 2012.

[schoen]

It's not clear this should be called an "exploit". It sounds like Microsoft in its capacity as a cryptographic endpoint turning over either plaintext or session keys (or in the severely worst case, long-term private keys). It doesn't make much sense to me to refer to that as an "exploit".

[ionised]

Actually, sorry that was the FBI they worked with.