Description
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.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | proftpd-dfsg | 1.3.2a-2 | — |
| Debian 13 | proftpd-dfsg | 1.3.2a-2 | — |
| Debian 12 | proftpd-dfsg | 1.3.2a-2 | — |
| Debian 5.0 | proftpd-dfsg | 1.3.1-17lenny4 | DSA-1925-1 |
| Debian 4.0 | proftpd-dfsg | 1.3.0-19etch3 | DSA-1925-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | proftpd | 1.3.5b-2.5 | openSUSE-SU-2024:10048-1 |
Advisories 2
- DSA-1925-1 proftpd-dfsg - SSL certificate verification weakness Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10048-1 proftpd-1.3.5b-2.5 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- [oss-security] 20091023 proftpd - mod_tls - Improper SSL/TLS certificate subjectAltName verification mailing-list
- FEDORA-2009-11666 vendor-advisory
- 37219 third-party-advisory
- FEDORA-2009-11649 vendor-advisory
- DSA-1925 vendor-advisory
- http://bugs.proftpd.org/show_bug.cgi?id=3275
- [oss-security] 20091023 Re: proftpd - mod_tls - Improper SSL/TLS certificate subjectAltName verification mailing-list
- 36804 vdb-entry
- proftpd-modtls-security-bypass(53936) vdb-entry
- 37131 third-party-advisory
- MDVSA-2009:288 vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=530719