gnutls is vulnerable to man-in-the-middle (MitM) attacks. The vulnerability exists as GnuTLS before 2.9.10 does not verify the activation and expiration dates of CA certificates, which allows man-in-the-middle attackers to spoof servers via a certificate issued by a CA certificate that is (1) not yet valid or (2) no longer valid.
rhn.redhat.com/errata/RHSA-2015-1457.html
www.securityfocus.com/bid/73317
access.redhat.com/errata/RHSA-2015:1457
access.redhat.com/security/cve/CVE-2014-8155
access.redhat.com/security/updates/classification/#moderate
bugzilla.redhat.com/show_bug.cgi?id=1036385
bugzilla.redhat.com/show_bug.cgi?id=1197995
gitlab.com/gnutls/gnutls/commit/897cbce62c0263a498088ac3e465aa5f05f8719c
rhn.redhat.com/errata/RHSA-2015-1457.html
support.f5.com/csp/article/K53330207