denyhosts 2.6 uses an incorrect regular expression when analyzing authentication logs, which allows remote attackers to cause a denial of service (incorrect block of IP addresses) via crafted login names.

debian · fedoraproject · phil_schwartz

DenyHosts 2.6 processes OpenSSH sshd "not listed in AllowUsers" log messages with an incorrect regular expression that does not match an IP address, which might allow remote attackers to avoid detection and blocking when making invalid login attempts with a username not present in AllowUsers, as demonstrated by the root username, a different vulnerability than CVE-2007-4323.

denyhosts

DenyHosts 2.6 does not properly parse sshd log files, which allows remote attackers to add arbitrary hosts to the /etc/hosts.deny file and cause a denial of service by adding arbitrary IP addresses to the sshd log file, as demonstrated by logging in via ssh with a client protocol version identification containing an IP address string, a different vector than CVE-2006-6301.

denyhosts