Build WildFly with necessary components containing this feature: https://github.com/fjuma/wildfly-elytron/tree/ELY-1706 https://github.com/undertow-io/undertow/tree/2.0.17.Final https://github.com/fjuma/wildfly-core/tree/WFCORE-4172 https://github.com/wildfly/wildfly/commit/4583669 Configure server-ssl-context allowing TLSv1.3 connect /subsystem=elytron/key-store=tls13:add(path=keystore.jks,relative-to=jboss.server.config.dir,credential-reference={clear-text=secret},type=JKS) /subsystem=elytron/key-store=tls13:generate-key-pair(alias=localhost,algorithm=RSA,key-size=1024,validity=365,credential-reference={clear-text=secret},distinguished-name= "CN=localhost" ) /subsystem=elytron/key-store=tls13:store() /subsystem=elytron/key-manager=tls13:add(key-store=tls13,credential-reference={clear-text=secret}) /subsystem=elytron/server-ssl-context=tls13:add(key-manager=tls13,protocols=[ "TLSv1.3" ]) batch /subsystem=undertow/server= default -server/https-listener=https:undefine-attribute(name=security-realm) /subsystem=undertow/server= default -server/https-listener=https:write-attribute(name=ssl-context,value=tls13) run-batch reload Send request to localhost while [ True ]; do curl --verbose --insecure --tlsv1.3 --http2 https: //localhost:8443; sleep 1; done Wait for the server to get stuck