The OAuth status rest resource in Atlassian Application Links before version 5.2.7, from 5.3.0 before 5.3.4 and from 5.4.0 before 5.4.3 allows remote attackers with administrative rights to access the content of internal network resources via a Server Side Request Forgery (SSRF) by creating an OAuth application link to a location they control and then redirecting access from the linked location's OAuth status rest resource to an internal location. When running in an environment like Amazon EC2, this flaw maybe used to access to a metadata resource that provides access credentials and other potentially confidential information.

The invalidRedirectUrl template in Atlassian Application Links before version 5.2.7, from version 5.3.0 before version 5.3.4 and from version 5.4.0 before version 5.4.3 allows remote attackers to inject arbitrary HTML or JavaScript via a cross site scripting (XSS) vulnerability in the redirectUrl parameter link in the redirect warning message.

Application Links before version 5.0.11, from version 5.1.0 before 5.2.10, from version 5.3.0 before 5.3.6, from version 5.4.0 before 5.4.12, and from version 6.0.0 before 6.0.4 allows remote attackers to inject arbitrary HTML or JavaScript via a cross site scripting (XSS) vulnerability in the applinkStartingUrl parameter. The product is used as a plugin in various Atlassian products where the following are affected: Confluence before version 6.15.2, Crucible before version 4.7.0, Crowd before version 3.4.3, Fisheye before version 4.7.0, Jira before version 7.13.3 and 8.x before 8.1.0.

The ListEntityLinksServlet resource in Application Links before version 5.0.12, from version 5.1.0 before version 5.2.11, from version 5.3.0 before version 5.3.7, from version 5.4.0 before 5.4.13, and from version 6.0.0 before 6.0.5 disclosed application link information to non-admin users via a missing permissions check.