SOPlanning does not verify uploaded file extension. An authenticated attacker with access to the backup functionality can upload a crafted ZIP archive containing a legitimate user.csv file alongside a malicious file, which is extracted on the server. When combined with CVE-2026-40547 (Path Traversal), the malicious file (e.g., a PHP script) can be placed in a web-accessible location and executed via the browser. This issue affects SOPlanning version 1.55 and below.
CWE-434