DenyHosts is a script intended to be run by Linux system administrators to help thwart SSH server attacks.
DenyHosts does not properly define the regular expressions used when parsing SSH authentication logs.
A remote attacker could possibly cause a Denial of Service condition via a crafted login name.
There is no known workaround at this time.
All DenyHost users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=app-admin/denyhosts-2.6-r9"