It was found that the AJP connector in undertow, as shipped in Jboss EAP 7.1.0.GA, does not use the ALLOW_ENCODED_SLASH option and thus allow the the slash / anti-slash characters encoded in the url which may lead to path traversal and result in the information disclosure of arbitrary local files.
https://bugzilla.redhat.com/show_bug.cgi?id=1534343
https://access.redhat.com/errata/RHSA-2018:0481
https://access.redhat.com/errata/RHSA-2018:0480