USN-5474-1 fixed vulnerabilities in Varnish Cache. Unfortunately the fix for CVE-2020-11653 was incomplete. This update fixes the problem.
Original advisory details:
It was discovered that Varnish Cache could have an assertion failure when a TLS termination proxy uses PROXY version 2. A remote attacker could possibly use this issue to restart the daemon and cause a performance loss. (CVE-2020-11653)
{
    "availability": "No subscription required",
    "binaries": [
        {
            "binary_version": "6.2.1-2ubuntu0.2",
            "binary_name": "libvarnishapi-dev"
        },
        {
            "binary_version": "6.2.1-2ubuntu0.2",
            "binary_name": "libvarnishapi2"
        },
        {
            "binary_version": "6.2.1-2ubuntu0.2",
            "binary_name": "varnish"
        }
    ]
}