CVE-2025-6689: FL3R Accessibility Suite XSS Vulnerability

CVE-2025-6689 Overview

The FL3R Accessibility Suite plugin for WordPress contains a stored Cross-Site Scripting (XSS) vulnerability in versions up to and including 1.4. The flaw exists in the plugin's fl3raccessibilitysuite shortcode, which fails to properly sanitize user-supplied attributes and escape output. Authenticated attackers with contributor-level access or higher can inject arbitrary JavaScript into pages. The injected scripts execute in the browser of any visitor who loads the affected page. This vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation).

Critical Impact
Authenticated contributors can inject persistent JavaScript that executes in the browsers of site visitors and administrators, enabling session theft, credential harvesting, and content manipulation.

Affected Products

FL3R Accessibility Suite plugin for WordPress, all versions through 1.4
WordPress sites running the plugin with contributor-level or higher user accounts
Any site permitting untrusted contributors to publish content containing shortcodes

Discovery Timeline

2025-06-27 - CVE-2025-6689 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-6689

Vulnerability Analysis

The vulnerability resides in how the FL3R Accessibility Suite plugin processes shortcode attributes within fl3raccessibilitysuite. WordPress shortcodes accept attributes as key-value pairs that the plugin renders into HTML output. The plugin passes these attributes to the page without adequate sanitization on input or escaping on output. As a result, any string supplied through the shortcode is rendered directly in the final HTML.

A contributor-level user can embed the shortcode in a post or page with attribute values containing HTML or JavaScript payloads. Once the post is viewed by another user, the browser parses and executes the injected script in the origin context of the WordPress site. This constitutes stored XSS because the payload persists in the WordPress database until manually removed.

The cross-scope impact reflects the ability of the injected script to affect users beyond the attacker, including administrators who preview or review contributor submissions.

Root Cause

The root cause is missing input sanitization and missing output escaping on shortcode attributes. The plugin does not apply WordPress security functions such as sanitize_text_field(), esc_attr(), or esc_html() to attribute values before rendering. This omission allows raw markup and script tags to reach the browser without neutralization.

Attack Vector

An attacker requires a WordPress account with contributor privileges or higher. The attacker creates or edits a post that includes the fl3raccessibilitysuite shortcode with malicious attribute values. When the post is submitted, saved, and later rendered, the browser executes the injected script. Because the scope changes from the plugin to the browser session of the visitor, an administrator viewing the content may unintentionally trigger actions such as account modification, arbitrary content publication, or plugin installation via authenticated requests.

No verified proof-of-concept code has been published. Refer to the Wordfence Vulnerability Report for additional technical context.

Detection Methods for CVE-2025-6689

Indicators of Compromise

Presence of the fl3raccessibilitysuite shortcode in wp_posts containing HTML tags, <script> blocks, javascript: URIs, or event handlers such as onerror and onload within attribute values
Unexpected outbound requests from visitor browsers to attacker-controlled domains after loading pages containing the shortcode
Newly created administrative users or modified user roles that coincide with contributor post submissions

Detection Strategies

Query the WordPress database for posts containing the vulnerable shortcode and inspect attribute values for HTML metacharacters and script keywords
Audit contributor and author accounts for recent post revisions that add or modify fl3raccessibilitysuite shortcodes
Review web server access logs for requests to pages containing the shortcode followed by anomalous administrator activity

Monitoring Recommendations

Enable WordPress activity logging to capture post creation, revision, and shortcode usage by non-administrator roles
Deploy a web application firewall with rules that detect script tags and event handlers within shortcode attributes
Monitor for creation of new administrator accounts, plugin installations, and theme edits following contributor content submissions

How to Mitigate CVE-2025-6689

Immediate Actions Required

Deactivate the FL3R Accessibility Suite plugin until a patched version is installed if no fix is currently available
Restrict contributor and author roles to trusted users and review recent posts for injected shortcode attributes
Purge any stored posts, revisions, and caches containing malicious fl3raccessibilitysuite shortcode payloads

Patch Information

At the time of publication, no fixed version is referenced in the available advisories. Review the WordPress Plugin Documentation and the Wordfence Vulnerability Report for updates on patched releases. Apply the vendor patch as soon as it becomes available and verify that installations are running a version later than 1.4.

Workarounds

Remove or disable the fl3raccessibilitysuite shortcode by unregistering it in a mu-plugin using remove_shortcode('fl3raccessibilitysuite')
Restrict shortcode usage to administrator and editor roles by filtering the_content and stripping the shortcode for lower-privileged authors
Deploy a web application firewall rule that blocks HTTP requests containing script tags or event handlers within shortcode attributes

bash

# Configuration example: disable the vulnerable shortcode via mu-plugin
# File: wp-content/mu-plugins/disable-fl3r-shortcode.php
<?php
add_action('init', function () {
    if (shortcode_exists('fl3raccessibilitysuite')) {
        remove_shortcode('fl3raccessibilitysuite');
    }
}, 100);