Advanced Coupons for WooCommerce Coupons <= 4.7.1.1 - Authenticated (Contributor+) Stored Cross-Site Scripting
Description
The Advanced Coupons for WooCommerce Coupons plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 4.7.1.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
CVSS Vector Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:NTechnical Details
<=4.7.1.1What Changed in the Fix
Changes introduced in v4.7.2
Source Code
WordPress.org SVN']` somewhere. * Is there any other Contributor-accessible area? * What about Coupon Categories? * `Edit_Coupon::override_coupon_categories_parent_file` - This is for the admin UI. * `Coupon_Templates::register_coupon_templates_app_page`. * Actually, let's look at `Edi…
Show full research plan
']` somewhere.
* Is there any other Contributor-accessible area?
* What about Coupon Categories?
* `Edit_Coupon::override_coupon_categories_parent_file` - This is for the admin UI.
* `Coupon_Templates::register_coupon_templates_app_page`.
* Actually, let's look at `Editor_Blocks.php`'s `render_coupons_by_category_block` again.
* It takes `categories` from `$attributes`.
* If `categories` is an array of IDs, no XSS.
* But what if it takes other attributes?
* I will provide a plan for both `acfw/single-coupon` and `acfw/coupons-category`.
* Wait, "Contributor" doesn't have `manage_woocommerce`.
* But they can edit "Posts".
* If they can edit "Posts", they can use "Blocks".
* This is the standard pattern for this type of vulnerability.
* Let's check if the plugin has any shortcodes.
* Gutenberg blocks usually have an equivalent shortcode.
* I don't see `add_shortcode` in the snippets, but `Editor_Blocks.php` handles block rendering.
* Wait, look at `Models/BOGO/Frontend.php`. `restrict_cart_
Summary
The Advanced Coupons for WooCommerce Coupons plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Gutenberg blocks. Authenticated attackers with contributor-level permissions can inject arbitrary web scripts into posts through unsanitized block attributes (such as custom CSS classes) that are later rendered on the frontend.
Vulnerable Code
// Helpers/Helper_Functions.php (approx line 1217 in version 4.7.1.1) if ( $classname ) { $classnames[] = $classname; } $this->load_template( // ...
Security Fix
@@ -735,6 +735,19 @@ } /** + * Sanitize a space-separated string of CSS class names. + * + * @since 4.6.2 + * @access public + * + * @param string $classes Space-separated CSS class names. + * @return array Array of sanitized class names. + */ + public function sanitize_css_classes( $classes ) { + return array_map( 'sanitize_html_class', explode( ' ', $classes ) ); + } + + /** * Prepare setting fields for API. * * @since 1.2 @@ -1217,7 +1230,7 @@ ); if ( $classname ) { - $classnames[] = $classname; + $classnames = array_merge( $classnames, $this->sanitize_css_classes( $classname ) ); } $this->load_template(
Exploit Outline
1. Authenticate to the WordPress site as a user with at least 'Contributor' level permissions. 2. Create a new Post or Page or edit an existing one. 3. Add one of the plugin's Gutenberg blocks, such as 'Advanced Coupons - Single Coupon' (`acfw/single-coupon`) or 'Advanced Coupons - Coupons Category' (`acfw/coupons-category`). 4. In the block's 'Advanced' settings tab, locate the 'Additional CSS class(es)' field. 5. Input a payload designed to break out of the HTML attribute context, such as: `" onmouseover="alert(1)" ` or `"><script>alert(document.domain)</script>`. 6. Save or Preview the post. The payload will be rendered on the frontend without proper sanitization, leading to script execution in the context of any user viewing the page.
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