CVE-2026-18933: wp-downloadmanager: Unrestricted File Upload via Missing Extension/MIME Validation and Path Traversal
The wp-downloadmanager WordPress plugin, in version 1.68.11 (also affecting the 6.9.4 release line), allows an admin-privileged user (currentusercan('managedownloads')) to upload arbitrary files via download-add.php with no extension or MIME-type validation of any kind - no wpcheckfiletypeandext(), no validatefile(), and no extension blocklist exist anywhere in the upload handler. The destination path is additionally built by concatenating the raw, unsanitized $POST['fileuploadto'] value with no traversal check (no ../ filtering, no basename()/realpath() applied). Since the base download path is required to live under WPCONTENTDIR (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 wpcheckfiletypeandext(), and v1.69.1 added directory-traversal protection - neither existed in 1.68.11.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
wp-downloadmanagerto a version that resolves this vulnerability.Fixed in 1.69.1 - Compensating control
Restrict access to download-add.php (and the wp-downloadmanager admin upload functionality) so only trusted admin-privileged users can reach it (since the vulnerability requires current_user_can('manage_downloads') and allows direct uploading to a web-servable path).
- Operational
Review and remove any files uploaded via download-add.php that may have been planted before upgrading (because arbitrary uploaded PHP files can be executed from the web-servable upload path).
Event History
Frequently Asked Questions
What is the severity of CVE-2026-18933?
CVE-2026-18933 has a high severity rating of 7.2.
How do I fix CVE-2026-18933?
To fix CVE-2026-18933, update the wp-downloadmanager plugin to the latest version that addresses this vulnerability.
Who is affected by CVE-2026-18933?
CVE-2026-18933 affects WordPress sites using the wp-downloadmanager plugin version 1.68.11 and the 6.9.4 release line.
What type of vulnerability is CVE-2026-18933?
CVE-2026-18933 is classified as a Malicious File Upload vulnerability.
What can be exploited in CVE-2026-18933?
CVE-2026-18933 allows users with admin privileges to upload files without restriction on extension or MIME-type.