---
id: CVE-2026-57857
title: >-
  The Flow Payment plugin for WordPress (flow.cl) version 3.0.8 is vulnerable to
  reflected cross-site scripting on the WooCommerce checkout page
summary: >-
  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 dire…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N'
cwe:
  - CWE-79
published: '2026-07-18'
updated: '2026-07-18'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-57857'
references:
  - url: 'https://www.flow.cl/'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/flow-payment-plugin-for-wordpress-reflected-cross-site-scripting-via-error-message-parameter
    label: disclosure@vulncheck.com
tags:
  - nvd
ingestedAt: '2026-07-19T08:30:40.216Z'
epss: 0.00336
epssPercentile: 0.24299
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.