WP Database Backup <= 7.11 - Authenticated (Administrator+) OS Command Injection via 'wp_db_exclude_table' Parameter

The WP Database Backup – Unlimited Database & Files Backup by Backup for WP plugin for WordPress is vulnerable to OS Command Injection in all versions up to and including 7.11 via the `wp_db_exclude_table` parameter. This is due to the direct concatenation of user-supplied `$_POST['wp_db_exclude_table']` values into the `mysqldump` shell command string in the `mysqldump()` function of `includes/admin/class-wpdb-admin.php` without wrapping them in `escapeshellarg()`—every other argument in the same command (DB_USER, DB_PASSWORD, host, filename, DB_NAME) is properly escaped, making the exclude-table values the sole exception—and because the only applied filtering, `sanitize_text_field()` via `recursive_sanitize_text_field()`, strips HTML tags but leaves shell metacharacters such as `;`, `|`, `` ` ``, and `$()` intact. This makes it possible for authenticated attackers, with administrator-level access and above, to execute arbitrary operating system commands on the server, potentially enabling full remote code execution. The injection is stored: malicious values submitted through the plugin settings form are persisted to the WordPress options table via `update_option('wp_db_exclude_table')` and later retrieved with `get_option()` and passed unsanitized to `shell_exec()` whenever a backup operation runs.

An attacker needs Administrator access first, so the firewall sees the attempt as traffic from a logged-in account: WordSec's web application firewall inspects request payloads before WordPress loads them. Classes like this one can leave something behind, so the staged malware scanner is the second half: it looks for dropped files and modified code rather than for the request that created them. None of that substitutes for the fix: WP Database Backup 7.12 closes this, and updating the plugin is the step that ends it.

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