Wazuh is a free and open source platform used for threat prevention, detection, and response. A wrong validation in the `host_deny` script allows to write any string in the `hosts.deny` file, which can end in an arbitrary command execution on the target system. This vulnerability is part of the active response feature, which can automatically triggers actions in response to alerts. By default, active responses are limited to a set of pre defined executables. This is enforced by only allowing executables stored under `/var/ossec/active-response/bin` to be run as an active response. However, the `/var/ossec/active-response/bin/host_deny` can be exploited. `host_deny` is used to add IP address to the `/etc/hosts.deny` file to block incoming connections on a service level by using TCP wrappers