Advisories for Composer/Phpoffice/Phpspreadsheet package

Bypassing the filter allows a XXE-attack. Which is turn allows attacker to obtain contents of local files, even if error reporting muted by @ symbol. (LFI-attack)

\PhpOffice\PhpSpreadsheet\Writer\Html doesn't sanitize spreadsheet styling information such as font names, allowing an attacker to inject arbitrary JavaScript on the page.

This affects the package phpoffice/phpspreadsheet from The library is vulnerable to XSS when creating an html output from an excel file by adding a comment on any cell. The root cause of this issue is within the HTML writer where user comments are concatenated as part of link and this is returned as HTML.

PHPOffice PhpSpreadsheet has an XXE issue. The XmlScanner decodes the sheet1.xml from an .xlsx to utf-8 if something else than UTF-8 is declared in the header. This was a security measurement to prevent CVE-2018-19277 but the fix is not sufficient. By double-encoding the the xml payload to utf-7 it is possible to bypass the check for the string ?<!ENTITY? and thus allowing for an xml external entity processing (XXE) attack.

securityScan() in PHPOffice PhpSpreadsheet allows a bypass of protection mechanisms for XXE via UTF-7 encoding in a .xlsx file.