CVE-2025-11856: Eventbee Ticketing Widget XSS Vulnerability

CVE-2025-11856 Overview

CVE-2025-11856 is a Stored Cross-Site Scripting (XSS) vulnerability in the Eventbee Ticketing Widget plugin for WordPress. The flaw affects all versions up to and including 1.0 and stems from missing input sanitization and output escaping in the eventbeeticketwidget shortcode. Authenticated users with contributor-level access or above can inject arbitrary JavaScript into pages. The malicious script executes in the browser of any user who visits an affected page. The vulnerability is tracked under CWE-79.

Critical Impact
Contributor-level attackers can inject persistent JavaScript that executes in visitors' browsers, enabling session theft, administrative account takeover, and site redirection.

Affected Products

Eventbee Ticketing Widget plugin for WordPress
All versions up to and including 1.0
WordPress sites permitting contributor-level or higher user registration

Discovery Timeline

2025-11-11 - CVE-2025-11856 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-11856

Vulnerability Analysis

The Eventbee Ticketing Widget plugin exposes the eventbeeticketwidget shortcode, which accepts multiple parameters that are rendered directly into page output. The plugin fails to sanitize these parameters on input and does not escape them on output. Authenticated users with contributor privileges can embed the shortcode within posts or pages and supply attacker-controlled values containing HTML or JavaScript.

When a visitor loads the injected page, the browser executes the payload in the context of the site's origin. Because the payload is stored in the WordPress database, every subsequent visit re-triggers execution. Attackers can leverage this to hijack administrator sessions, exfiltrate cookies, perform CSRF actions against privileged users, or pivot to full site takeover. The scope-changed nature of the flaw indicates payloads can affect components beyond the vulnerable plugin's boundary.

Root Cause

The root cause is missing sanitization and escaping in the shortcode handler defined in ticket-widget.php. Shortcode attributes are concatenated into HTML output without calls to esc_attr(), esc_html(), or wp_kses(). This falls under CWE-79: Improper Neutralization of Input During Web Page Generation.

Attack Vector

An attacker first obtains contributor-level access, which many WordPress sites grant through open registration or guest-author workflows. The attacker then creates a post containing the eventbeeticketwidget shortcode with malicious parameter values, for example script payloads placed inside attributes such as event identifiers. Once an editor previews the draft, or the post is published and visited, the injected script executes with the visitor's privileges. Additional details are available in the Wordfence advisory.

Detection Methods for CVE-2025-11856

Indicators of Compromise

Posts or pages containing eventbeeticketwidget shortcode instances with attribute values that include <script>, onerror=, onload=, or javascript: sequences
Unexpected outbound requests from visitor browsers to attacker-controlled domains originating from pages using the plugin
Newly created administrator accounts or unexplained privilege changes following contributor activity
WordPress audit log entries showing contributor-authored posts with unusually long or encoded shortcode attributes

Detection Strategies

Query the wp_posts table for post_content values matching the shortcode pattern and inspect attributes for HTML control characters
Deploy a web application firewall rule that flags shortcode parameters containing script tags or event handlers
Review contributor and author account activity for atypical post creation patterns

Monitoring Recommendations

Monitor WordPress role changes and administrator account creation in near real time
Alert on Content Security Policy (CSP) violation reports referencing inline script execution on pages using the plugin
Track file integrity for wp-content/plugins/eventbee-ticketing-widget/ to identify unauthorized modifications

How to Mitigate CVE-2025-11856

Immediate Actions Required

Deactivate and remove the Eventbee Ticketing Widget plugin until a patched version is released by the vendor
Audit all existing posts and pages for occurrences of the eventbeeticketwidget shortcode and remove untrusted content
Restrict contributor-level registrations and review recently registered low-privilege accounts
Rotate administrator session cookies and credentials if injection is suspected

Patch Information

At the time of publication, no patched version beyond 1.0 is listed in the advisory. Monitor the Wordfence vulnerability record and the WordPress plugin repository for a fixed release.

Workarounds

Remove the plugin entirely and replace its functionality with a vendor-maintained alternative
Restrict shortcode usage by revoking the edit_posts capability from untrusted contributor accounts
Deploy a Content Security Policy that disallows inline scripts to reduce exploitability of stored XSS payloads
Configure a WAF rule to strip or block shortcode attributes containing <, >, or javascript: tokens

bash

# Disable and remove the vulnerable plugin using WP-CLI
wp plugin deactivate eventbee-ticketing-widget
wp plugin uninstall eventbee-ticketing-widget

# Audit posts for the vulnerable shortcode
wp db query "SELECT ID, post_title, post_author FROM wp_posts \
  WHERE post_content LIKE '%[eventbeeticketwidget%';"