PhpSpreadsheet: XmlScanner Bypass via Double-Encoded unentity() TOCTOU Allows XXE and Denial of Service

影響: composer:phpoffice/phpspreadsheet >= 4.0.0, <= 5.9.0 → 5.10.0, composer:phpoffice/phpspreadsheet >= 3.3.0, <= 3.10.7 → 3.10.8

The SpreadsheetML XML reader (Reader\Xml) scans file content twice through XmlScanner::scan(), and each scan runs an unentity() callback that calls html_entity_decode() after the pattern check. By double-encoding the toUtf8($xml); if (preg_match($pattern, $xml)) { // CHECK 2 (UTF-8) throw new Exception('Detected use of ENTITY...'); } if ($this->callback !== null) { $xml = call_user_func($this->callback, $xml); // DECODE (after checks!) } return $xml; // getSecurityScannerOrThrow()->scan($data);…

Read on GitHub Advisory Database

On 10/28/2026, 12:38 AM, GitHub Advisory Database published "PhpSpreadsheet: XmlScanner Bypass via Double-Encoded unentity() TOCTOU Allows XXE and Denial of Service" (type: Advisory). Severity is "High" (high). Related technologies: PHP. CVE: CVE-2026-108357.