USN-2639-1: OpenSSL vulnerabilities

Praveen Kariyanahalli, Ivan Fratric and Felix Groebert discovered that OpenSSL incorrectly handled memory when buffering DTLS data. A remote attacker could use this issue to cause OpenSSL to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2014-8176) Joseph Barr-Pixton discovered that OpenSSL incorrectly handled malformed ECParameters structures. A remote attacker could use this issue to cause OpenSSL to hang, resulting in a denial of service. (CVE-2015-1788) Robert Swiecki and Hanno Böck discovered that OpenSSL incorrectly handled certain ASN1TIME strings. A remote attacker could use this issue to cause OpenSSL to crash, resulting in a denial of service. (CVE-2015-1789) Michal Zalewski discovered that OpenSSL incorrectly handled missing content when parsing ASN.1-encoded PKCS#7 blobs. A remote attacker could use this issue to cause OpenSSL to crash, resulting in a denial of service. (CVE-2015-1790) Emilia Käsper discovered that OpenSSL incorrectly handled NewSessionTicket when being used by a multi-threaded client. A remote attacker could use this issue to cause OpenSSL to crash, resulting in a denial of service. (CVE-2015-1791) Johannes Bauer discovered that OpenSSL incorrectly handled verifying signedData messages using the CMS code. A remote attacker could use this issue to cause OpenSSL to hang, resulting in a denial of service. (CVE-2015-1792) As a security improvement, this update also modifies OpenSSL behaviour to reject DH key sizes below 768 bits, preventing a possible downgrade attack.