It was discovered that the ElytronManagedThread in Wildfly's Elytron subsystem in versions from 11 to 16 stores a SecurityIdentity to run the thread as. These threads do not necessarily terminate if the keep alive time has not expired. This could allow a shared thread to use the wrong security identity when executing.
https://security.netapp.com/advisory/ntap-20190517-0004/
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-3894
https://access.redhat.com/errata/RHSA-2019:1140
https://access.redhat.com/errata/RHSA-2019:1108