This indicates an attack attempt to exploit a Remote Code Execution vulnerability in Nexus Repository Manager 3.
The vulnerability is due to improper authentication in the vulnerable application when handling a malicious request. A remote attacker may be able exploit this to execute arbitrary code on vulnerable machines.
Nexus Repository Manager 3.6.2 OSS/Pro versions up to and including 3.14.0
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.