The new "ssl-security-level" option allows one to change the OpenSSL
security level without having to change the openssl.cnf global file of
your distribution. This directives applies on every SSL_CTX context.
People sometimes change their security level directly in the ciphers
directive, however there are some cases when the security level change
is not applied in the right order (for example when applying a DH
param).
Before this patch, it was to possible to trick by using a specific
openssl.cnf file and start haproxy this way:
OPENSSL_CONF=./openssl.cnf ./haproxy -f bug-2468.cfg
Values for the security level can be found there:
https://www.openssl.org/docs/man1.1.1/man3/SSL_CTX_set_security_level.html
This was discussed in github issue #2468.