CVE-2009-3639: n/a vulnerability

CVE-2009-3639: The mod_tls module in ProFTPD before 1.3.2b, and 1.3.3 before 1.3.3rc2, when the dNSNameRequired TLS option...

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.

UnknownCVSS not scoredNot KEV-listedUpdatedAug 7, 2024, 06:38 UTC (UTC+00:00)

Security readout for executives and security teams

CVE-2009-3639 is an old ProFTPD TLS client-certificate validation flaw. In specific configurations, a certificate with a null character in a Subject Alternative Name could bypass hostname-based client restrictions. Risk is concentrated on ProFTPD servers using mod_tls with dNSNameRequired enabled. Exposure is likely limited to ProFTPD deployments using mod_tls client certificates with the dNSNameRequired TLS option enabled. Internet-facing or partner-facing FTPS services using affected versions deserve priority review. Prioritize remediation where ProFTPD FTPS is exposed and client certificates are used for access control. Legacy systems are the main concern; unaffected configurations are lower urgency. Mitigation focus: Upgrade ProFTPD to 1.3.2b, 1.3.3rc2, or later.; Apply relevant vendor updates from Debian, Fedora, Mandriva, or your distribution.; Review ProFTPD mod_tls configuration for dNSNameRequired usage..

Prepared: Jun 28, 2026, 18:15 UTC (UTC+00:00)

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

Potential ATT&CK relevance

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Vulnerability profileCVE Program record

Severity: Unknown
CVSS: Not scored
Known Exploited: No
Published: Oct 28, 2009, 14:00 UTC (UTC+00:00)

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors

0Timeline events

0ADP providers

5Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

CVE List V5 sourceCVE List V5
FEDORA-2009-11666CVE reference · vendor-advisory, x_refsource_FEDORA
FEDORA-2009-11649CVE reference · vendor-advisory, x_refsource_FEDORA
proftpd-modtls-security-bypass(53936)CVE reference · vdb-entry, x_refsource_XF
https://bugzilla.redhat.com/show_bug.cgi?id=530719CVE reference · x_refsource_CONFIRM

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus

n/an/an/aListed

Weakness

CWE details

No CWE listed

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