Atlassian Crowd and Crowd Data Center had the pdkinstall development plugin incorrectly enabled in release builds. Attackers who can send unauthenticated or authenticated requests to a Crowd or Crowd Data Center instance can exploit this vulnerability to install arbitrary plugins, which permits remote code execution on systems running a vulnerable version of Crowd or Crowd Data Center. All versions of Crowd from version 2.1.0 before 3.0.5 (the fixed version for 3.0.x), from version 3.1.0 before 3.1.6 (the fixed version for 3.1.x), from version 3.2.0 before 3.2.8 (the fixed version for 3.2.x), from version 3.3.0 before 3.3.5 (the fixed version for 3.3.x), and from version 3.4.0 before 3.4.4 (the fixed version for 3.4.x) are affected by this vulnerability.

The console login resource in Atlassian Crowd before version 3.0.2 and from version 3.1.0 before version 3.1.1 allows remote attackers, who have previously obtained a user's JSESSIONID cookie, to gain access to some of the built-in and potentially third party rest resources via a session fixation vulnerability.

The administration backup restore resource in Atlassian Crowd before version 3.0.2 and from version 3.1.0 before version 3.1.1 allows remote attackers to read files from the filesystem via a XXE vulnerability.

The login resource of CrowdId in Atlassian Crowd before version 3.0.2 and from version 3.1.0 before version 3.1.1 allows remote attackers to redirect users to a different website which they may use as part of performing a phishing attack via an open redirect.