Stored XSS in SOPlanning

SOPlanning is vulnerable to Stored Cross-Site Scripting (XSS) via /process/upload_backup endpoint. An authenticated attacker with access to the backup functionality can upload a crafted ZIP archive containing a malicious user.csv file with embedded JavaScript. The injected code is executed in the victim’s browser when a user clicks the Edit button for the malicious backup. This issue affects SOPlanning version 1.55 and below.