In Ceph before 12.2.3 and 13.x through 13.0.1, the rgw_civetweb.cc RGWCivetWeb::init_env function in radosgw doesn't handle malformed HTTP headers properly, allowing for denial of service.
https://github.com/ceph/ceph/pull/20488
https://bugzilla.redhat.com/show_bug.cgi?id=1546611
https://access.redhat.com/errata/RHSA-2018:0548