A vulnerability was found in Apache HTTP Server 2.4.34 to 2.4.38. When HTTP/2 was enabled for a http: host or H2Upgrade was enabled for h2 on a https: host, an Upgrade request from http/1.1 to http/2 that was not the first request on a connection could lead to a misconfiguration and crash. Server that never enabled the h2 protocol or that only enabled it for https: and did not set "H2Upgrade on" are unaffected by this issue.
Exploitability
AV:NAC:HPR:LUI:NScope
S:UImpact
C:NI:LA:L4.2/CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L