PHPOffice PhpSpreadsheet before 1.8.0 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.
| Package (Ecosystem) | Introduced | Fixed | Limit |
|---|---|---|---|
| phpoffice/phpspreadsheet(Packagist) | 0 | 1.8.0 | N/A |
| phpoffice/phpexcel(Packagist) | 0 | N/A | N/A |
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