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

2015-06-04T04:00:00
ID RHSA-2015:1072
Type redhat
Reporter RedHat
Modified 2018-06-06T20:24:12

Description

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.