A flaw was found in the way HAProxy processed HTTP responses containing the "Set-Cookie2" header. This flaw could allow an attacker to send crafted HTTP response packets which lead to an infinite loop, eventually resulting in a denial of service condition. The highest threat from this vulnerability is availability.
https://www.mail-archive.com/haproxy%40formilux.org/msg41833.html
https://www.debian.org/security/2022/dsa-5102
https://github.com/haproxy/haproxy/commit/bfb15ab34ead85f64cd6da0e9fb418c9cd14cee8