Internet2 Shibboleth Service Provider software 1.3.x before 1.3.3 and 2.x before 2.2.1, when using PKIX trust validation, does not properly handle a '\0' character in the subject or subjectAltName fields of a certificate, which allows remote 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.