CVE-2009-3639: ProFTPD

Medium severity, CVSS 5.8. EPSS: 5.7% chance of exploitation in the next 30 days.

The mod_tls module in ProFTPD before 1.3.2b, and 1.3.3 before 1.3.3rc2, when the dNSNameRequired TLS option is enabled, does not properly handle a '\0' character in a domain name in the Subject Alternative Name field of an X.509 client certificate, which allows remote attackers to bypass intended client-hostname restrictions via a crafted certificate issued by a legitimate Certification Authority, a related issue to CVE-2009-2408.

Affected products

• ProFTPD ProFTPD: up to and including 1.3.2; version 1.3.1 only; version 1.3.2 only; version 1.3.3 only

Published 2009-10-28. Last modified 2026-06-16.