USN-4203-1 fixed a vulnerability in NSS. This update provides the corresponding update for Ubuntu 12.04 ESM and Ubuntu 14.04 ESM.
Original advisory details:
It was discovered that NSS incorrectly handled certain memory operations. A remote attacker could use this issue to cause NSS to crash, resulting in a denial of service, or possibly execute arbitrary code.
2:3.28.4-0ubuntu0.14.04.5+esm2