Some HTTP/2 implementations are vulnerable to unconstrained interal data
buffering, potentially leading to a denial of service. The attacker opens
the HTTP/2 window so the peer can send without constraint; however, they
leave the TCP window closed so the peer cannot actually write (many of) the
bytes on the wire. The attacker then sends a stream of requests for a large
response object. Depending on how the servers queue the responses, this can
consume excess memory, CPU, or both.
Disable http2 support
sbeattieapache2 2.4.18 in xenial does not build mod_http2
Upstream:released (2.4.41-1)
Ubuntu 12.04 ESM (Precise Pangolin):not-affected (http2 support not implemented)
Ubuntu 14.04 ESM (Trusty Tahr):not-affected (http2 support not implemented)
Ubuntu 16.04 LTS (Xenial Xerus):not-affected (code not built)
Ubuntu 18.04 LTS (Bionic Beaver):released (2.4.29-1ubuntu4.10)
More Information

Updated: 2020-10-28 16:55:04 UTC (commit 61c466688be673cb43da2af6d4295f1a01fd7ad1)