Webmin 2.510 is vulnerable to a Host Header Injection in the password reset functionality (forgot_send.cgi). The reset link sent to users is constructed using the HTTP Host header via get_webmin_email_url(). An attacker can manipulate the Host header to inject a malicious domain into the reset email. If a victim follows the poisoned link, the attacker can intercept the reset token and gain full control of the target account.