Network Security Services (NSS) is a set of libraries designed to support cross-platform development of security-enabled client and serverapplications.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 toforce 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 NSS toreject DH key sizes below 768 bits, which prevents sessions to bedowngraded to export-grade keys. Future updates may raise this limit to1024 bits.The nss and nss-util packages have been upgraded to upstream versions3.19.1. The upgraded versions provide a number of bug fixes andenhancements over the previous versions.Users of nss and nss-util are advised to upgrade to these updated packages,which fix these security flaws, bugs, and add these enhancements.