CVE-2021-23351

The package github.com/pires/go-proxyproto before 0.5.0 are vulnerable to
Denial of Service (DoS) via the parseVersion1() function. The reader in
this package is a default bufio.Reader wrapping a net.Conn. It will read
from the connection until it finds a newline. Since no limits are
implemented in the code, a deliberately malformed V1 header could be used
to exhaust memory in a server process using this code - and create a DoS.
This can be exploited by sending a stream starting with PROXY and
continuing to send data (which does not contain a newline) until the target
stops acknowledging. The risk here is small, because only trusted sources
should be allowed to send proxy protocol headers.