This indicates an attack attempt to exploit an Elevation of Privilege vulnerability in Katello and in Red Hat Satellite.
The vulnerability is due to an error when the vulnerable server handles a maliciously crafted HTTP request. Remote authenticated attackers may be able to exploit this to escalate their privilege on vulnerable systems.
katello version 1.5.0-14 and prior
Privilege Escalation: Remote attackers can leverage their privileges on vulnerable systems.
Apply the most recent upgrade or patch from the vendor.