All actively supported release lines are vulnerable and the severity is LOW. An attacker can cause a Denial of Service (DoS) by establishing an HTTP or HTTPS connection in keep-alive mode and by sending headers very slowly thereby keeping the connection and associated resources alive for a long period of time. Attack potential is mitigated by the use of a load balancer or other proxy layer. This vulnerability is an extension of CVE-2018-12121, addressed in November, 2018. The 40 second timeout and its adjustment by server.headersTimeout apply to this fix as in CVE-2018-12121.