Atlassian Jira Server and Data Center before version 8.7.0 use a version of the Atlassian Application Links plugin that is vulnerable to cross-site request forgery (CSRF). An attacker could exploit this by tricking an administrative user into making malicious HTTP requests, allowing the attacker to enumerate hosts and open ports on the internal network where the Jira server is present. See https://ecosystem.atlassian.net/browse/APL-1390 for further details.