USN-4397-1 fixed a vulnerability in NSS. This update provides the corresponding update for Ubuntu 12.04 ESM and Ubuntu 14.04 ESM.
Original advisory details:
Cesar Pereida Garcia discovered that NSS incorrectly handled DSA key generation. A local attacker could possibly use this issue to perform a timing attack and recover DSA keys. (CVE-2020-12399)
2:3.28.4-0ubuntu0.14.04.5+esm5