GHSA-3j5q-7q7h-2hhv

The product custom option file upload in OpenMage LTS uses an incomplete blocklist (forbidden_extensions = php,exe) to prevent dangerous file uploads. This blocklist can be trivially bypassed by using alternative PHP-executable extensions such as .phtml, .phar, .php3, .php4, .php5, .php7, and .pht. Files are stored in the publicly accessible media/custom_options/quote/ directory, which lacks server-side execution restrictions for some configurations, enabling Remote Code Execution if this directory is not explicitly denied script execution.

Affected Version

• Project: OpenMage/magento-lts
• Vulnerable File: https://github.com/OpenMage/magento-lts/blob/main/app/code/core/Mage/Catalog/Model/Product/Option/Type/File.php
• Vulnerable Lines: 230-237 (_validateUploadedFile())
• Configuration: app/code/core/Mage/Catalog/etc/config.xml:824

Root Cause

The file upload handler uses Zend_File_Transfer_Adapter_Http directly with ExcludeExtension validator, referencing only:

<!-- Catalog/etc/config.xml:824 -->
<forbidden_extensions>php,exe</forbidden_extensions>

This misses the comprehensive protected_extensions blocklist defined elsewhere:

<!-- Core/etc/config.xml:449-478 -->
php, php3, php4, php5, php7, htaccess, jsp, pl, py, asp, sh, cgi, 
htm, html, pht, phtml, shtml

Vulnerable Code

// app/code/core/Mage/Catalog/Model/Product/Option/Type/File.php:230-237
$_allowed = $this->_parseExtensionsString($option->getFileExtension());
if ($_allowed !== null) {
    $upload->addValidator('Extension', false, $_allowed);
} else {
    $_forbidden = $this->_parseExtensionsString($this->getConfigData('forbidden_extensions'));
    if ($_forbidden !== null) {
        $upload->addValidator('ExcludeExtension', false, $_forbidden);  // Only blocks php,exe!
    }
}

Steps to Reproduce

1. Environment Setup

Target: OpenMage LTS with Apache+mod_php or Apache+PHP-FPM (with .phtml handler)

2....