USN-5672-1 fixed a vulnerability in GMP. This update provides the corresponsing update for Ubuntu 14.04 ESM.
Original advisory details:
It was discovered that GMP did not properly manage memory on 32-bit platforms when processing a specially crafted input. An attacker could possibly use this issue to cause applications using GMP to crash, resulting in a denial of service.
{
    "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
    "binaries": [
        {
            "binary_name": "libgmp-dev",
            "binary_version": "2:5.1.3+dfsg-1ubuntu1+esm1"
        },
        {
            "binary_name": "libgmp10",
            "binary_version": "2:5.1.3+dfsg-1ubuntu1+esm1"
        },
        {
            "binary_name": "libgmp3-dev",
            "binary_version": "2:5.1.3+dfsg-1ubuntu1+esm1"
        },
        {
            "binary_name": "libgmpxx4ldbl",
            "binary_version": "2:5.1.3+dfsg-1ubuntu1+esm1"
        }
    ]
}