USN-612-3 addressed a weakness in OpenSSL certificate and key generation and introduced openssl-blacklist to aid in detecting vulnerable certificates and keys. This update adds RSA-4096 blacklists to the openssl-blacklist-extra package and adjusts openssl-vulnkey to properly handle RSA-4096 and higher moduli.
Original advisory details: A weakness has been discovered in the random number generator used by OpenSSL on Debian and Ubuntu systems. As a result of this weakness, certain encryption keys are much more common than they should be, such that an attacker could guess the key through a brute-force attack given minimal knowledge of the system. This particularly affects the use of encryption keys in OpenSSH, OpenVPN and SSL certificates.