CVE-2025-39482

Executive Summary

CVE-2025-39482 is a Missing Authorization vulnerability in the Eventer WordPress plugin by imithemes. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized access to sensitive event data or functionality. The vulnerability affects all versions of Eventer prior to 3.11.4. The CVSS score is 4.3 (Medium), and the EPSS probability is 0.0%, indicating low active exploitation in the wild. No public proof-of-concept (PoC) or exploit code is currently available.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin ecosystem. The Eventer plugin is distributed via the official WordPress plugin repository and third-party marketplaces. Organizations using this plugin should verify their version and apply any available patches immediately. Since the patch status is unknown, users must monitor the vendor’s channels for updates.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
• Base Score: 4.3 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)

Threat Level: Medium. The vulnerability is easy to exploit remotely without authentication, but the impact is limited to low confidentiality loss. No integrity or availability impact.

Deep Dive & Mechanics

The vulnerability stems from Missing Authorization (CWE-862) in the Eventer plugin. The plugin fails to properly enforce access control checks on certain AJAX actions or REST endpoints, allowing unauthenticated users to access or modify event data that should be restricted to administrators or authenticated users.

Root Cause: The plugin likely uses wp_ajax_nopriv_* hooks without verifying user capabilities, or it exposes functions that do not call current_user_can() or wp_verify_nonce().

Attack Vector: An attacker can send crafted HTTP requests to the vulnerable endpoints, bypassing authentication checks. For example, an endpoint that retrieves event details or modifies event settings may be accessible without a valid session.

Impact: Unauthorized disclosure of event information (e.g., attendee lists, private event details) or potential manipulation of event data if write operations are also unprotected.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical comparison based on common fixes for missing authorization vulnerabilities.

Vulnerable Code (Eventer < 3.11.4):

add_action('wp_ajax_nopriv_eventer_get_event', 'eventer_get_event');
function eventer_get_event() {
    $event_id = $_GET['event_id'];
    // No capability check
    $event = get_post($event_id);
    echo json_encode($event);
    wp_die();
}

Patched Code (Eventer >= 3.11.4):

add_action('wp_ajax_nopriv_eventer_get_event', 'eventer_get_event');
function eventer_get_event() {
    if (!current_user_can('read_event')) {
        wp_die('Unauthorized', 403);
    }
    $event_id = intval($_GET['event_id']);
    $event = get_post($event_id);
    echo json_encode($event);
    wp_die();
}

The patched version adds a capability check (current_user_can()) and validates the input.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target WordPress site with Eventer plugin version < 3.11.4.
• Network access to the site.

Exploitation Steps:

1. Identify vulnerable endpoints by analyzing the plugin’s AJAX actions (e.g., eventer_get_event, eventer_update_event).
2. Send a crafted HTTP request without authentication:

   curl -X GET "http://target.com/wp-admin/admin-ajax.php?action=eventer_get_event&event_id=1"
   

3. If successful, the response will contain event data (e.g., JSON with event details).

Note: No public exploit code is available. The above is a generic example.

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with action parameters related to Eventer (e.g., eventer_*).
• Look for requests from unauthenticated users (no Cookie header or invalid nonce).
• Analyze logs for 403 errors after patching.

Defense:

• Update Eventer to version 3.11.4 or later.
• If no patch is available, disable the plugin or restrict access to its endpoints via a Web Application Firewall (WAF).
• Implement additional authentication checks using a security plugin (e.g., Wordfence).

Indicators of Compromise (IOCs)

• HTTP Requests:
  • GET /wp-admin/admin-ajax.php?action=eventer_get_event&event_id=<ID>
  • POST /wp-admin/admin-ajax.php with action=eventer_update_event
• Log Entries:
  • Repeated 200 responses to admin-ajax.php from unknown IPs without authentication.
• File Changes:
  • Unauthorized modifications to event posts in the database.

Detection Engineering

YARA Rule

rule CVE_2025_39482_Eventer_Missing_Auth {
    meta:
        description = "Detects exploitation attempts for CVE-2025-39482 in Eventer plugin"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-39482"
    strings:
        $ajax_action = "action=eventer_" nocase
        $admin_ajax = "admin-ajax.php" nocase
    condition:
        $ajax_action and $admin_ajax
}

Sigma Rule

title: CVE-2025-39482 Eventer Missing Authorization Exploitation
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects unauthenticated AJAX requests to Eventer plugin endpoints
author: Valters IT
date: 2025-04-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 'admin-ajax.php?action=eventer_'
    condition: selection
falsepositives:
    - Legitimate admin actions (requires authentication)
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-39482 Eventer Missing Authorization Attempt"; flow:to_server; content:"admin-ajax.php"; http_uri; content:"action=eventer_"; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update Eventer to version 3.11.4 or later if a patch becomes available.
2. Disable the plugin if no patch is available and the plugin is not critical.
3. Implement a WAF rule to block requests to admin-ajax.php with action parameters starting with eventer_ from unauthenticated users.

Long-term Measures:

• Regularly update all WordPress plugins and themes.
• Conduct security audits of custom or third-party plugins.
• Use a security plugin that monitors for missing authorization vulnerabilities.

Valters IT Signature This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.