This indicates an attempt to execute a payload on Atlassian Jira via the Universal Plugin Manager.
Jira Universal Plugin Manager is designed for helping users manage their apps. An attacker with system administrator privileges could upload a malicious plugin through the plugin manager, leading to further attacks.
Atlassian Jira via the Universal Plugin Manager
System Compromise: Authenticated attackers can gain control of vulnerable systems.
Restrict and audit the access to the Universal plugin manager