OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL v2/v3)and Transport Layer Security (TLS v1) protocols, as well as afull-strength, general purpose cryptography library.An out-of-bounds read flaw was found in the X509_cmp_time() function ofOpenSSL. A specially crafted X.509 certificate or a Certificate RevocationList (CRL) could possibly cause a TLS/SSL server or client using OpenSSLto crash. (CVE-2015-1789)A NULL pointer dereference was found in the way OpenSSL handled certainPKCS#7 inputs. A specially crafted PKCS#7 input with missingEncryptedContent data could cause an application using OpenSSL to crash.(CVE-2015-1790)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 to 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.Red Hat would like to thank the OpenSSL project for reporting CVE-2015-1789and CVE-2015-1790. Upstream acknowledges Robert Swiecki and Hanno B?ck asthe original reporters of CVE-2015-1789, and Michal Zalewski as theoriginal reporter of CVE-2015-1790.All openssl users are advised to upgrade to these updated packages, whichcontain backported patches to correct these issues. For the update to takeeffect, all services linked to the OpenSSL library must be restarted, orthe system rebooted.