(RHSA-2015:1072) Moderate: openssl security update

OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL v2/v3)
and Transport Layer Security (TLS v1) protocols, as well as a
full-strength, general purpose cryptography library.

A flaw was found in the way the TLS protocol composes the Diffie-Hellman
(DH) key exchange. A man-in-the-middle attacker could use this flaw to
force the use of weak 512 bit export-grade keys during the key exchange,
allowing them do decrypt all traffic. (CVE-2015-4000)

Note: This update forces the TLS/SSL client implementation in OpenSSL to
reject DH key sizes below 768 bits, which prevents sessions to be
downgraded to export-grade keys. Future updates may raise this limit to
1024 bits.

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.