What happened
A vulnerability disclosed on April 7, 2014 in a widely used encryption library could have allowed an attacker to read memory from affected servers. Every relay was patched and given new transport keys within a day.
Message content was never at risk: Glossia messages are encrypted end to end before they reach any relay, and the transport keys protect only the connection between relays. We replaced the keys anyway, because that is what the people relying on the network would expect.