This indicates an attack attempt to exploit an Authentication Bypass Vulnerability in SolarWinds Orion Platform.
The vulnerability is due to insufficient handling of specific path components in request-URIs. A remote, unauthenticated attacker can exploit this vulnerability by sending a crafted request to the target system. Successful exploitation results in the attacker gaining access to certain API endpoints which would normally require authentication.
SolarWinds Orion Platform 2019.2 HF 3 and prior
SolarWinds Orion Platform 2019.4 prior to HF 6
SolarWinds Orion Platform 2020.2.x prior to 2020.2.1 HF 2
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.