gnutls -- X.509 certificate chain validation vulnerability

SecurityFocus reports:

GnuTLS is prone to a security-bypass vulnerability because the
application fails to properly validate chained X.509 certificates.
Successfully exploiting this issue allows attackers to perform
man-in-the-middle attacks by impersonating trusted servers.
Unsuspecting users may be under a false sense of security that can
aid attackers in launching further attacks.