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. An out-of-bounds read flaw was found in the X509_cmp_time function of OpenSSL. A specially crafted X.509 certificate or a Certificate Revocation List could possibly cause a TLS/SSL server or client using OpenSSL to crash. A NULL pointer dereference was found in the way OpenSSL handled certain PKCS#7 inputs. A specially crafted PKCS#7 input with missing EncryptedContent data could cause an application using OpenSSL to crash. A flaw was found in the way the TLS protocol composes the Diffie-Hellman 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 to decrypt all traffic. 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. Red Hat would like to thank the OpenSSL project for reporting CVE-2015-1789 and CVE-2015-1790. Upstream acknowledges Robert Swiecki and Hanno Bock as the original reporters of CVE-2015-1789, and Michal Zalewski as the original reporter of CVE-2015-1790. All openssl users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. For the update to take effect, all services linked to the OpenSSL library must be restarted, or the system rebooted.