CVE-2013-6890: denyhosts 2.6 uses an incorrect regular expression when analyzing authentication logs, which allows remote...

Security readout for executives and security teams

CVE-2013-6890 is a flaw in DenyHosts 2.6 that can make the tool block the wrong IP addresses. An attacker can use crafted login names in authentication attempts to influence log parsing, potentially locking out legitimate users or administrators rather than compromising the server directly. Exposure is most likely on systems running DenyHosts 2.6 or vendor packages derived from it, especially where automated SSH blocking can affect administrator access. The bundle does not identify affected CPEs or all downstream package versions. Treat this as an availability and access-continuity issue. It is not described as code execution, but it can disrupt operations by blocking legitimate access on protected systems. Prioritize internet-facing SSH hosts and administrative jump points. Mitigation focus: Check vendor advisories for the DenyHosts package on each affected distribution.; Apply available vendor security updates, including guidance associated with Debian DSA-2826.; Review DenyHosts configuration for operational risk from automatic IP blocking..

Prepared

Jun 14, 2026, 15:13 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.