CVE-2013-4314: Canonical Ubuntu Linux

Medium severity, CVSS 4.3. EPSS: 1.2% chance of exploitation in the next 30 days.

The X509Extension in pyOpenSSL before 0.13.1 does not properly handle a '\0' character in a domain name in the Subject Alternative Name field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority.

Affected products

• Canonical Ubuntu Linux: version 10.04 only; version 12.04 only; version 12.10 only; version 13.04 only
• Jean-Paul Calderone Pyopenssl: up to and including 0.13; version 0.7 only; version 0.8 only; version 0.9 only; version 0.10 only; version 0.11 only; …

Published 2013-09-30. Last modified 2026-06-16.