Plane: Cross-Project Asset Hijacking via 'ProjectBulkAssetEndpoint' (sibling of CVE-2026-46558)

Plane is an open-source project management tool. Prior to 1.4.0, ProjectBulkAssetEndpoint.post in apps/api/plane/app/views/asset/v2.py retrieves assets using id__in=asset_ids and workspace__slug=slug but does not constrain the query with project_id from the URL. A workspace Guest can provide asset UUIDs from another project in the same workspace and reassign their issue_id, comment_id, page_id, draft_issue_id, or project_id to an entity the attacker controls. Plane then treats the attacker's project as the new owner and provides a presigned download URL for the hijacked file. This issue is fixed in 1.4.0.