The EditApplinkServlet resource in the Atlassian Application Links plugin before version 5.4.20, from version 6.0.0 before version 6.0.12, from version 6.1.0 before version 6.1.2, from version 7.0.0 before version 7.0.1, and from version 7.1.0 before version 7.1.3 allows remote attackers who have obtained access to administrator's session to access the EditApplinkServlet resource without needing to re-authenticate to pass "WebSudo" in products that support "WebSudo" through an improper access control vulnerability.

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.

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 OAuthHelper in Atlassian Application Links before version 5.0.10, from version 5.1.0 before version 5.1.3, and from version 5.2.0 before version 5.2.6 used an XML document builder that was vulnerable to XXE when consuming a client OAuth request. This allowed malicious oauth application linked applications to probe internal network resources by requesting internal locations, read the contents of files and also cause an out of memory exception affecting availability via an XML External Entity vulnerability.

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.

Various administrative application link resources in Atlassian Application Links before version 5.4.4 allow remote attackers with administration rights to inject arbitrary HTML or JavaScript via a cross site scripting (XSS) vulnerability in the display url of a configured application link.

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.