Red Hat Security Advisory 2016-0008-01 – OpenSSL is a toolkit that implements the Secure Sockets Layer and Transport Layer Security protocols, as well as a full-strength, general purpose cryptography library. 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 openssl 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 OpenSSL library must be restarted, or the system rebooted.