neon before 0.28.6, when OpenSSL or GnuTLS is used, does not properly handle a \'\0\' character in a domain name in the subject\'s Common Name (CN) 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, a related issue to CVE-2009-2408.