CVE-2006-6301: Denyhosts

Medium severity, CVSS 5.0. EPSS: 1.9% chance of exploitation in the next 30 days.

DenyHosts 2.5 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 login name containing certain strings with an IP address, which is not properly handled by a regular expression.

Affected products

• Denyhosts Denyhosts: version 2.5 only

Published 2006-12-06. Last modified 2026-06-16.