Keep Backup Daily WordPress Plugin Stored Cross-Site Scripting Vulnerability

A stored cross-site scripting vulnerability has been identified in the Keep Backup Daily plugin for WordPress, affecting all versions through 2.1.2. The issue arises in the 'update_kbd_bkup_alias' AJAX action, where the backup title alias parameter lacks proper input sanitization and output escaping. Although 'sanitize_text_field()' removes HTML tags when saving, it fails to encode double quotes. Consequently, backup titles are rendered in HTML attribute contexts without using 'esc_attr()', allowing authenticated attackers with Administrator-level access to inject arbitrary web scripts via attribute injection. These scripts execute when another administrator views the backup list page.

Impact

Exploitation of this vulnerability allows for stored cross-site scripting, where injected scripts are executed in the context of the user viewing the backup list.

Reproduction

To reproduce this vulnerability, an authenticated user with Administrator privileges can send a request to the 'update_kbd_bkup_alias' AJAX action. The request must include the 'val' parameter with a crafted backup title alias that contains the desired script injection. Once the injection is processed, the script will execute when the backup list page is viewed by an administrator.

Remediation

Users are advised to update the Keep Backup Daily WordPress plugin to version 2.1.3 or later.