This code was vulnerable to ping floods, potentially leading to a denial of service. The attacker sends continual pings to an HTTP/2 peer, causing the peer to build an internal queue of responses. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both (CVE-2019-9512).
This code was vulnerable to a reset flood, potentially leading to a denial of service. The attacker opens a number of streams and sends an invalid request over each stream that should solicit a stream of RSTSTREAM frames from the peer. Depending on how the peer queues the RSTSTREAM frames, this can consume excess memory, CPU, or both (CVE-2019-9514).