Inside a Jira instance **any user** \(even **non-authenticated**\) can **check its privileges** in `/rest/api/2/mypermissions` or `/rest/api/3/mypermissions` . These endpoints will return your current privileges.
If a **non-authenticated** user have any **privilege**, this is a **vulnerability** \(bounty?\).
If an **authenticated** user have any **unexpected privilege**, this a a **vuln**.