PhpOffice/PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. Prior to versions 1.30.0, 2.1.12, 2.4.0, 3.10.0, and 5.0.0, SSRF can occur when a processed HTML document is read and displayed in the browser. The vulnerability lies in the setPath method of the PhpOfficePhpSpreadsheetWorksheetDrawing class, where a crafted string from the user is passed to the HTML reader. This issue has been patched in versions 1.30.0, 2.1.12, 2.4.0, 3.10.0, and 5.0.0.
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.