BNC is an IRC proxying server
A flaw exists in the input parsing of BNC where part of the sbuf_getmsg() function handles the backspace character incorrectly.
A remote user could issue commands using fake authentication credentials and possibly gain access to scripts running on the client side.
There is no known workaround at this time.
All BNC users should upgrade to the latest version:
# emerge sync
# emerge -pv ">=net-irc/bnc-2.8.9"
# emerge ">=net-irc/bnc-2.8.9"