CVE-2013-6890

CVE-2013-6890 describes a denial-of-service vulnerability in DenyHosts 2.6, affecting various Debian and Fedora distributions. An attacker can exploit an incorrect regular expression in authentication log analysis by using crafted login names, leading to the incorrect blocking of legitimate IP addresses. This vulnerability has a CVSS score of 5.0 (medium severity) with a low attack complexity and no authentication required, resulting in a partial availability impact. While there is no evidence of active exploitation or inclusion in the KEV catalog, an exploit is publicly available on ExploitDB, though there is minimal community discussion or media coverage.