CVE-2025-6681: Fan Page Plugin for WordPress XSS Vulnerability

CVE-2025-6681 Overview

CVE-2025-6681 is a Stored Cross-Site Scripting (XSS) vulnerability affecting the Fan Page plugin for WordPress. The flaw exists in all versions up to and including 1.0.1. It stems from insufficient input sanitization and output escaping on the width parameter, categorized as [CWE-79].

Authenticated users with Contributor-level permissions or higher can inject arbitrary web scripts into pages. The injected payload executes in the browser of any visitor who loads the affected page. Successful exploitation enables session theft, forced redirects, and administrative action abuse through authenticated victim sessions.

Critical Impact

Authenticated contributors can persist malicious JavaScript that runs against site visitors and administrators, enabling account takeover and content tampering.

Affected Products

• Fan Page plugin for WordPress — all versions up to and including 1.0.1
• WordPress sites allowing Contributor-level registration
• WordPress installations that permit plugin shortcode use by non-admin roles

Discovery Timeline

• 2025-07-29 - CVE-2025-6681 published to the National Vulnerability Database (NVD)
• 2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-6681

Vulnerability Analysis

The Fan Page plugin exposes a shortcode or configuration input that accepts a width parameter. The plugin writes this value into rendered HTML without sufficient sanitization on input or escaping on output. An authenticated attacker supplies crafted JavaScript inside the width value, and the plugin stores it in the post or page content.

When any user loads the affected page, the browser parses the injected markup and executes the attacker's script in the site's origin. Because the payload runs in an authenticated administrator's session, it can issue privileged requests, create accounts, or modify plugin settings. The stored nature of the flaw means a single injection persists until the content is manually cleaned.

Root Cause

The plugin treats the width parameter as a trusted layout value instead of untrusted user input. It neither validates the input against a numeric or dimensional pattern nor applies escaping functions such as esc_attr() before rendering it into HTML attributes.

Attack Vector

Exploitation requires authenticated access with Contributor permissions or higher. The attacker edits or creates a post containing the vulnerable shortcode, inserting a JavaScript payload inside the width attribute. After publishing, the payload executes in every viewer's browser session. No user interaction beyond page navigation is required to trigger the stored script. Full technical details are available in the Wordfence Vulnerability Report.

Detection Methods for CVE-2025-6681

Indicators of Compromise

• Unexpected <script> tags, event handlers (onerror, onload), or javascript: URIs within post or page content stored in wp_posts
• Fan Page shortcodes containing non-numeric values in the width attribute
• Outbound requests from administrator browsers to unfamiliar domains after loading plugin-rendered pages
• New administrator accounts or modified user roles created shortly after a Contributor publishes content

Detection Strategies

• Query the WordPress database for shortcodes referencing the Fan Page plugin and inspect parameter values for non-whitelisted characters
• Enable a Content Security Policy (CSP) in report-only mode to surface inline script execution on plugin-rendered pages
• Review audit logs for Contributor-level users who recently edited or created pages containing plugin shortcodes

Monitoring Recommendations

• Monitor WordPress audit logs for post revisions by low-privilege users that include HTML attribute injection patterns
• Alert on administrator sessions that trigger unexpected XHR or fetch calls to the WordPress REST API
• Track plugin version inventory across managed WordPress sites and flag installations running Fan Page 1.0.1 or earlier

How to Mitigate CVE-2025-6681

Immediate Actions Required

• Deactivate the Fan Page plugin on any site running version 1.0.1 or earlier until a patched release is confirmed
• Audit existing posts and pages for malicious width parameter values and remove any injected payloads
• Restrict Contributor-level registrations and review recent role assignments for suspicious activity
• Rotate administrator credentials and invalidate active sessions if injected scripts are discovered

Patch Information

No fixed version is referenced in the available advisories at publication time. Review the WordPress Plugin Developer Info page for release updates and apply any version newer than 1.0.1 as soon as it is published.

Workarounds

• Remove or replace the Fan Page plugin with a maintained alternative
• Restrict shortcode usage by limiting post editing permissions to Editor and Administrator roles
• Deploy a web application firewall rule that blocks shortcode parameters containing <, >, or script keywords
• Enforce a strict Content Security Policy to prevent inline script execution site-wide

# Configuration example: disable the plugin via WP-CLI
wp plugin deactivate fan-page
wp plugin delete fan-page