CVE-2026-18933 in Wp-downloadmanager Plugin
Summary
by MITRE • 08/05/2026
The wp-downloadmanager WordPress plugin, in version 1.68.11 (also affecting the 6.9.4 release line), allows an admin-privileged user (current_user_can('manage_downloads')) to upload arbitrary files via download-add.php with no extension or MIME-type validation of any kind - no wp_check_filetype_and_ext(), no validate_file(), and no extension blocklist exist anywhere in the upload handler. The destination path is additionally built by concatenating the raw, unsanitized $_POST['file_upload_to'] value with no traversal check (no ../ filtering, no basename()/realpath() applied). Since the base download path is required to live under WP_CONTENT_DIR (a web-accessible location), an uploaded PHP file lands in a web-servable path and can be directly executed, resulting in remote code execution. The plugin's own later changelog confirms these protections were absent in this version: v1.69 added file-type validation via wp_check_filetype_and_ext(), and v1.69.1 added directory-traversal protection - neither existed in 1.68.11.
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Analysis
by VulDB Data Team • 08/05/2026
The wp-downloadmanager WordPress plugin vulnerability represents a critical security flaw that enables administrative privilege escalation through arbitrary file upload capabilities. This vulnerability specifically affects version 1.68.11 and the 6.9.4 release line, where the plugin fails to implement essential file validation mechanisms that would normally prevent malicious uploads. The flaw exists within the download-add.php handler which processes file uploads without any form of extension or MIME-type validation, creating an attack surface that directly violates fundamental web security principles.
The technical implementation of this vulnerability stems from the complete absence of input sanitization measures within the upload processing logic. The plugin does not invoke WordPress core functions such as wp_check_filetype_and_ext() or validate_file() to verify file integrity and type before storage. Additionally, there are no extension blocklists implemented to prevent the upload of potentially dangerous file types including php, phps, phtml, or other executable formats. The destination path construction process further compounds this issue by directly concatenating the unsanitized $_POST['file_upload_to'] parameter with the base download directory path, without any traversal protection mechanisms.
The operational impact of this vulnerability is severe and directly translates to remote code execution capabilities for authenticated administrators. Since the plugin requires files to be stored within WP_CONTENT_DIR, which is web-accessible, any uploaded PHP file becomes immediately executable through direct URL access. This creates a persistent backdoor that can be exploited by attackers who have gained administrative credentials or through credential compromise scenarios. The vulnerability effectively bypasses standard web application security controls by leveraging legitimate administrative functionality to achieve malicious code execution.
Security professionals should note that this vulnerability aligns with CWE-434 Unrestricted Upload of File with Dangerous Type and follows patterns identified in ATT&CK technique T1505.003 Server Software Component. The absence of proper file validation and path traversal protection in version 1.68.11 represents a clear failure in secure coding practices that would normally be enforced through input validation and output encoding controls. According to WordPress security guidelines, all plugin developers must implement strict file type validation and sanitization before allowing any file uploads to occur. The fact that subsequent versions (1.69 and 1.69.1) addressed these issues demonstrates the recognized severity of the flaw and provides a clear mitigation pathway for affected users.
The recommended remediation strategy involves immediate plugin version upgrade to 1.69.1 or later, which implements both file-type validation through wp_check_filetype_and_ext() and directory traversal protection. Organizations should also implement additional monitoring for unusual file upload activities within their WordPress installations and consider implementing web application firewalls to detect and block suspicious file upload attempts. Security teams should conduct thorough audits of all installed plugins to identify similar vulnerabilities and ensure that administrative users follow principle of least privilege practices to minimize potential damage from compromised accounts.