It is possible to set max-concurrent-requests attribute of request limit filter in undertow to value lower than one ------------------------------------------------------------------------------------------------------------------- Key: WFLY-7718 URL: https://issues.jboss.org/browse/WFLY-7718 Project: WildFly Issue Type: Bug Components: Web (Undertow) Reporter: Stuart Douglas Assignee: Stuart Douglas According to https://github.com/undertow-io/undertow/blob/master/core/src/main/java/io... it should not be possible to perform this operation: {{/subsystem=undertow/configuration=filter/request-limit=foo:add(max-concurrent-requests=-42)}} so it looks like no value check is performed in this case.