The Apache HTTP Server 2.4.17 and 2.4.18, when mod_http2 is enabled, does not limit the number of simultaneous stream workers for a single HTTP/2 connection, which allows remote attackers to cause a denial of service (stream-processing outage) via modified flow-control windows.
Exploitability
AV:NAC:HPR:NUI:NScope
S:UImpact
C:NI:NA:H5.9/CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H