CVE-2026-28027: ThemeREX Kayon LFI Vulnerability

CVE-2026-28027 Overview

CVE-2026-28027 is a PHP Local File Inclusion (LFI) vulnerability affecting the ThemeREX Kayon WordPress theme. The vulnerability stems from improper control of filename for include/require statements in PHP, allowing attackers to include local files on the server. This weakness (CWE-98) enables unauthorized access to sensitive files and could potentially lead to remote code execution under certain conditions.

Critical Impact

This Local File Inclusion vulnerability in the Kayon WordPress theme could allow attackers to read sensitive configuration files, access credentials, or chain with other vulnerabilities to achieve code execution on affected WordPress installations.

Affected Products

• ThemeREX Kayon WordPress Theme version 1.3 and earlier
• WordPress installations using vulnerable Kayon theme versions

Discovery Timeline

• 2026-03-05 - CVE-2026-28027 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-28027

Vulnerability Analysis

This vulnerability is classified as CWE-98: Improper Control of Filename for Include/Require Statement in PHP Program. The Kayon WordPress theme fails to properly validate and sanitize user-controlled input before using it in PHP include or require statements. This allows an attacker to manipulate the file path parameter to include arbitrary local files from the server's filesystem.

Local File Inclusion vulnerabilities in PHP applications are particularly dangerous in WordPress environments, as they can expose sensitive files such as wp-config.php (containing database credentials), .htaccess files, or other configuration data. In some scenarios, attackers can leverage LFI to achieve remote code execution by including log files that contain injected PHP code or by utilizing PHP wrapper protocols.

Root Cause

The root cause of this vulnerability is insufficient input validation in the Kayon theme's file inclusion logic. The theme accepts user-controllable parameters that are directly or indirectly passed to PHP's include(), require(), include_once(), or require_once() functions without proper sanitization. This allows path traversal sequences (such as ../) to be used to navigate outside the intended directory and access sensitive files elsewhere on the server.

Attack Vector

An attacker can exploit this vulnerability by crafting malicious requests to the vulnerable WordPress theme endpoints. By manipulating file path parameters, the attacker can traverse directories and include sensitive local files. Common attack techniques include:

The exploitation typically involves manipulating URL parameters or POST data to inject path traversal sequences. Attackers commonly target files such as /etc/passwd on Linux systems to confirm the vulnerability, and then escalate to more sensitive files like WordPress configuration files. The attack does not require authentication, making it accessible to remote unauthenticated attackers in most configurations. For detailed technical information, refer to the Patchstack vulnerability database entry.

Detection Methods for CVE-2026-28027

Indicators of Compromise

• Unusual HTTP requests containing path traversal patterns (../, ..%2f, %2e%2e/) targeting Kayon theme endpoints
• Web server logs showing attempts to access sensitive files like /etc/passwd, wp-config.php, or .htaccess
• Unexpected file read operations originating from the WordPress theme directory
• Error logs indicating failed file inclusion attempts with non-standard paths

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block path traversal patterns in requests
• Monitor web server access logs for requests containing directory traversal sequences targeting theme files
• Deploy file integrity monitoring on critical WordPress configuration files
• Use WordPress security plugins that detect LFI attack patterns in real-time

Monitoring Recommendations

• Enable detailed logging for WordPress and web server access logs
• Configure alerts for access attempts to sensitive system files from web application contexts
• Monitor for unusual PHP error logs that may indicate failed exploitation attempts
• Implement network-level monitoring for outbound connections that may indicate post-exploitation activity

How to Mitigate CVE-2026-28027

Immediate Actions Required

• Update the Kayon WordPress theme to a patched version if available from ThemeREX
• If no patch is available, consider temporarily disabling or removing the Kayon theme
• Implement WAF rules to block path traversal patterns targeting the vulnerable theme
• Review web server logs for signs of exploitation attempts
• Audit WordPress installations for unauthorized file access or modifications

Patch Information

This vulnerability affects ThemeREX Kayon theme versions through 1.3. Users should check with ThemeREX for updated versions that address this vulnerability. Monitor the Patchstack vulnerability advisory for patch availability and additional guidance.

Workarounds

• Implement strict input validation at the web server level using ModSecurity or similar WAF solutions
• Use PHP's open_basedir directive to restrict file access to the WordPress directory only
• Deploy SentinelOne Singularity to detect and prevent exploitation attempts at runtime
• Restrict access to the WordPress admin and theme directories using IP-based access controls
• Consider using a Content Delivery Network (CDN) with built-in WAF capabilities to filter malicious requests

# Example Apache .htaccess rules to block common LFI patterns
<IfModule mod_rewrite.c>
    RewriteEngine On
    # Block path traversal attempts
    RewriteCond %{QUERY_STRING} \.\.\/ [NC,OR]
    RewriteCond %{QUERY_STRING} \.\.%2f [NC,OR]
    RewriteCond %{QUERY_STRING} %2e%2e\/ [NC,OR]
    RewriteCond %{QUERY_STRING} %2e%2e%2f [NC]
    RewriteRule ^(.*)$ - [F,L]
</IfModule>