Flow Payment Plugin up to 3.0.8 Checkout flowpayment-fl.php wc_add_notice error_message cross site scripting

Summaryinfo

A vulnerability labeled as problematic has been found in Flow Payment Plugin up to 3.0.8. This affects the function wc_add_notice of the file flowpayment-fl.php of the component Checkout. Such manipulation of the argument error_message leads to cross site scripting. This vulnerability is documented as CVE-2026-57857. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Flow Payment Plugin up to 3.0.8. It has been rated as problematic. Affected by this issue is the function wc_add_notice of the file flowpayment-fl.php of the component Checkout. The manipulation of the argument error_message with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. CVE summarizes:

The Flow Payment plugin for WordPress (flow.cl) version 3.0.8 is vulnerable to reflected cross-site scripting on the WooCommerce checkout page. When the plugin handles an order cancellation, the error_message GET parameter is passed directly to wc_add_notice() in flowpayment-fl.php (lines 57-58) without input sanitization (for example sanitize_text_field()) or output escaping (for example esc_html()) before being rendered in the checkout notice HTML. An unauthenticated attacker can craft a URL containing a JavaScript payload in the error_message parameter (for example /checkout/?add-to-cart={product-id}&cancel_order=true&error_message={payload}); when a victim with an active WooCommerce checkout session follows the link, the payload executes in the victim's browser in the origin of the WordPress site.

This vulnerability is handled as CVE-2026-57857 since 06/25/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1059.007.

By approaching the search of inurl:flowpayment-fl.php it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 3.0.9 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-45400). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

• Flow

Name

• Payment Plugin

Version

• 3.0.0
• 3.0.1
• 3.0.2
• 3.0.3
• 3.0.4
• 3.0.5
• 3.0.6
• 3.0.7
• 3.0.8

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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