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 ?
{ "nvd_published_at": "2019-11-07T15:15:10Z", "cwe_ids": [ "CWE-611" ], "severity": "HIGH", "github_reviewed": true, "github_reviewed_at": "2019-11-19T03:41:04Z" }