Vulnerability Instance

PHPOffice Math allows XXE when processing an XML file in the MathML format
**Product:** Math
**Version:** 0.2.0
**CWE-ID:** CWE-611: Improper Restriction of XML External Entity Reference
**CVSS vector v.4.0:** 8.7 (AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N)
**CVSS vector v.3.1:** 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
**Description:** An attacker can create a special XML file, during which it processed, external entities are loaded, and it’s possible to read local server files.
**Impact:** Local server files reading
**Vulnerable component:** The [`loadXML`](https://github.com/PHPOffice/Math/blob/c3ecbf35601e2a322bf2ddba48589d79ac827b92/src/Math/Reader/MathML.php#L38C9-L38C55) function with the unsafe [`LIBXML_DTDLOAD`](https://www.php.net/manual/en/libxml.constants.php#constant.libxml-dtdload) flag, the [`MathML`](https://github.com/PHPOffice/Math/blob/master/src/Math/Reader/MathML.php) class
**Exploitation conditions:** The vulnerability applies only to reading a file in the `MathML` format.
**Mitigation:** If there is no option to refuse using the [`LIBXML_DTDLOAD`](https://www.php.net/manual/en/libxml.constants.php#constant.libxml-dtdload) flag, it’s recommended to filter external entities through the implementation of the [`custom external entity loader function`](https://www.php.net/manual/en/function.libxml-set-external-entity-loader.php).
**Researcher: Aleksandr Zhurnakov (Positive Technologies)**