The Netic User Export add-on before 1.3.5 for Atlassian Confluence has the functionality to generate a list of users in the application, and export it. During export, the HTTP request has a fileName parameter that accepts any file on the system (e.g., an SSH private key) to be downloaded.
In the Netic User Export add-on before 1.3.5 for Atlassian Confluence, authorization is mishandled. An unauthenticated attacker could access files on the remote system.
Refer to Gist GitHub for patch, upgrade or suggested workaround information.