Elasticsearch Security versions 6.5.0 and 6.5.1 contain an XXE flaw in
Machine Learning's find_file_structure API. If a policy allowing external
network access has been added to Elasticsearch's Java Security Manager then
an attacker could send a specially crafted request capable of leaking
content of local files on the Elasticsearch node. This could allow a user
to access information that they should not have access to.