gnutls-cli in GnuTLS before 2.6.6 does not verify the activation and expiration times of X.509 certificates, which allows remote attackers to successfully present a certificate that is (1) not yet valid or (2) no longer valid, related to lack of time checks in the _gnutls_x509_verify_certificate function in lib/x509/verify.c in libgnutls_x509, as used by (a) Exim, (b) OpenLDAP, and (c) libsoup.
https://exchange.xforce.ibmcloud.com/vulnerabilities/50261
http://www.vupen.com/english/advisories/2009/1218
http://www.securitytracker.com/id?1022159
http://www.securityfocus.com/bid/34783
http://www.mandriva.com/security/advisories?name=MDVSA-2009:116
http://security.gentoo.org/glsa/glsa-200905-04.xml
http://secunia.com/advisories/35211
http://secunia.com/advisories/34842
http://article.gmane.org/gmane.comp.encryption.gpg.gnutls.devel/3517