OpenSSH is a complete SSH protocol implementation that includes SFTP client and server support.
It was discovered that OpenSSH was prone to a user enumeration vulnerability.
A remote attacker could conduct user enumeration.
There is no known workaround at this time.
All OpenSSH users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-misc/openssh-7.7_p1-r8"