Design/Logic Flaw

Cloudflare Quiche (through version 0.19.1/0.20.0) was affected by an unlimited resource allocation vulnerability causing rapid increase of memory usage of the system running quiche server or client.
A remote attacker could take advantage of this vulnerability by repeatedly sending an unlimited number of 1-RTT CRYPTO frames after previously completing the QUIC handshake.
Exploitation was possible for the duration of the connection which could be extended by the attacker. 
quiche 0.19.2 and 0.20.1 are the earliest versions containing the fix for this issue.