Sophia (point release 6)
Dozens of upstream performance, reliability and security patches
Improved packaging for (unfinished/non-usable) Ledger wallet support
Several documentation improvements from the AEON community
Disable incorrect/obsolete DNS lookups
All users running nodes on the p2p network should update ASAP to prevent DoS attacks against the nodes.
All users receiving payments should update ASAP to protect against the cryptonote duplicate output coin burning attack described in https://getmonero.org/2018/09/25/a-post-mortum-of-the-burning-bug.html (if unable to update immediately, suspend receiving payments until updated).