USN-3990-1 fixed a vulnerability in urllib3. This update provides the corresponding update for Ubuntu 14.04 ESM.
Original advisory details:
It was discovered that urllib3 incorrectly stripped certain characters from requests. A remote attacker could use this issue to perform CRLF injection. (CVE-2019-11236)
{
    "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
    "binaries": [
        {
            "binary_name": "python-urllib3",
            "binary_version": "1.7.1-1ubuntu4.1+esm1"
        },
        {
            "binary_name": "python-urllib3-whl",
            "binary_version": "1.7.1-1ubuntu4.1+esm1"
        },
        {
            "binary_name": "python3-urllib3",
            "binary_version": "1.7.1-1ubuntu4.1+esm1"
        }
    ]
}