USN-4288-1 fixed a vulnerability in ppp. This update provides the corresponding update for Ubuntu 12.04 ESM and Ubuntu 14.04 ESM.
Original advisory details:
It was discovered that ppp incorrectly handled certain rhostname values. A remote attacker could use this issue to cause ppp to crash, resulting in a denial of service, or possibly execute arbitrary code.
2.4.5-5.1ubuntu2.3+esm1