CVE-2025-13746: ForumWP WordPress Plugin XSS Vulnerability

CVE-2025-13746 Overview

The ForumWP – Forum & Discussion Board plugin for WordPress contains a Stored Cross-Site Scripting (XSS) vulnerability in the User's Display Name functionality. This vulnerability affects all versions up to and including 2.1.6 and stems from insufficient input sanitization and output escaping when handling user display names. Authenticated attackers with Subscriber-level access or above can exploit this flaw to inject arbitrary web scripts into pages, which execute whenever any user accesses the compromised page.

Critical Impact

Authenticated attackers can inject persistent malicious scripts that execute in victims' browsers, potentially leading to session hijacking, credential theft, or malware distribution across the WordPress forum.

Affected Products

• ForumWP – Forum & Discussion Board plugin for WordPress versions ≤ 2.1.6
• WordPress installations with ForumWP plugin enabled
• Any WordPress site allowing subscriber-level user registration with ForumWP active

Discovery Timeline

• 2026-01-06 - CVE CVE-2025-13746 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2025-13746

Vulnerability Analysis

This Stored Cross-Site Scripting vulnerability exists due to the plugin's failure to properly sanitize user-supplied input in the Display Name field before storing it in the database, and the subsequent failure to escape this data when rendering it in the browser. The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation).

The attack requires only basic authenticated access (Subscriber-level), making it particularly concerning for WordPress forums that allow public user registration. Once malicious script content is injected into the display name field, it persists in the database and executes in the context of any user's session when they view a page containing the attacker's display name—such as forum posts, user profiles, or user cards.

Root Cause

The root cause lies in multiple components of the ForumWP plugin that handle user display name data without proper security controls. The vulnerability chain involves the class-user.php file, the user-card.php template, and the tooltip.js frontend script. The user class retrieves display name data from the database without sanitization, the user card template renders this data directly into HTML without escaping special characters, and the tooltip JavaScript processes this unsanitized data for display. This multi-point failure allows script payloads embedded in display names to be interpreted as executable code by the browser.

Attack Vector

The attack is network-based and requires low complexity to execute. An attacker first creates or uses an existing WordPress account with at least Subscriber-level privileges on a site running the vulnerable ForumWP plugin. The attacker then modifies their Display Name to include malicious JavaScript code. When this crafted display name is rendered in forum posts, user cards, tooltips, or other areas where user names appear, the injected script executes in the browsers of other users viewing that content.

The malicious payload persists in the WordPress database, making this a Stored XSS attack that affects multiple victims without requiring the attacker to maintain an active presence. The scope is changed as the vulnerability in the ForumWP plugin can impact the broader WordPress installation context.

Detection Methods for CVE-2025-13746

Indicators of Compromise

• Unusual characters or script tags present in user display names within the wp_users or related ForumWP database tables
• Browser console errors or unexpected script execution when viewing forum pages or user profiles
• User complaints about popup windows, redirects, or suspicious behavior when browsing forum content
• Audit log entries showing unusual display name changes to include encoded or script-like content

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect XSS payloads in POST requests to user profile update endpoints
• Review ForumWP user data in the database for suspicious patterns including <script>, javascript:, onerror=, or encoded equivalents
• Deploy Content Security Policy (CSP) headers with strict script-src directives to prevent inline script execution
• Monitor browser-based security telemetry for blocked XSS attempts via CSP violation reports

Monitoring Recommendations

• Enable detailed logging for user profile modification events within WordPress
• Configure real-time alerting for CSP violations reported from forum pages
• Implement periodic automated scans of user-generated content fields for XSS payload signatures
• Monitor network traffic for data exfiltration attempts that may indicate successful XSS exploitation

How to Mitigate CVE-2025-13746

Immediate Actions Required

• Update the ForumWP plugin to a version newer than 2.1.6 when a patch becomes available
• Audit existing user display names in the database for any malicious content and sanitize as needed
• Implement strict Content Security Policy headers to mitigate the impact of any undetected XSS payloads
• Consider temporarily restricting subscriber registration or display name modification capabilities until patched

Patch Information

At the time of publication, organizations should monitor the Wordfence Vulnerability Analysis for patch availability and update guidance. The vulnerable code paths can be reviewed in the WordPress plugin repository at tooltip.js, class-user.php, and user-card.php.

Workarounds

• Deploy a Web Application Firewall with XSS detection rules to filter malicious input before it reaches the application
• Implement server-side input validation and output encoding for all user-controllable fields rendered by ForumWP
• Add Content Security Policy headers with script-src 'self' to prevent execution of inline scripts
• Restrict the ability for subscribers to modify display names through WordPress role customization or plugin modifications

# Example Content Security Policy header configuration for Apache
# Add to .htaccess or virtual host configuration
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; frame-ancestors 'self';"