OpenSSH is a complete SSH protocol implementation that includes an SFTP client and server support.
Two issues have been discovered in OpenSSH:
A local attacker could exploit the first vulnerability to hijack forwarded X11 sessions of other users and possibly execute code with their privileges, disclose sensitive data or cause a Denial of Service, by binding a local X11 server to a port using only one address family. The second vulnerability might allow local attackers to bypass intended security restrictions and execute commands other than those specified by "ForceCommand" if they are able to write to their home directory.
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-4.7_p1-r6"