Plane is an open-source project management tool. Prior to 1.4.0, BulkDeleteIssuesEndpoint and SubIssuesEndpoint in apps/api/plane/app/views/issue/ accept body- or URL-supplied issue IDs and operate on them without checking that the IDs belong to the caller's workspace and project. The permission decorator on each endpoint validates only that the caller is a member or administrator of the workspace and project named in the URL. BulkDeleteIssuesEndpoint can destroy CycleIssue and ModuleIssue associations belonging to foreign issues. SubIssuesEndpoint can re-parent foreign issues under an attacker-selected issue and return the foreign issues' metadata. This issue is fixed in 1.4.0.