Red Hat Security Advisory 2016-0007-01 – Network Security Services is a set of libraries designed to support the cross-platform development of security-enabled client and server applications. A flaw was found in the way TLS 1.2 could use the MD5 hash function for signing ServerKeyExchange and Client Authentication packets during a TLS handshake. A man-in-the-middle attacker able to force a TLS connection to use the MD5 hash function could use this flaw to conduct collision attacks to impersonate a TLS server or an authenticated TLS client. All nss users are advised to upgrade to these updated packages, which contain a backported patch to correct this issue. For the update to take effect, all services linked to the NSS library must be restarted, or the system rebooted.