CVE-2026-18933: File Upload RCE (CVSS 7.2)

Description

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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CVSS v3.1 Score

7.2

HIGH

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Weakness Type (CWE)

CWE-434 Unrestricted Upload

References

Other References

https://wordpress.org/plugins/wp-downloadmanager/#description

Frequently Asked Questions

What is CVE-2026-18933? +

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. It has a CVSS v3.1 base score of 7.2 (HIGH).

How severe is CVE-2026-18933? +

CVE-2026-18933 has a CVSS v3.1 score of 7.2 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

How do I check if I'm vulnerable to CVE-2026-18933? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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