CVE-2026-28023: ThemeREX Nuts LFI Vulnerability

CVE-2026-28023 Overview

CVE-2026-28023 is a PHP Local File Inclusion (LFI) vulnerability affecting the ThemeREX Nuts WordPress theme. The vulnerability stems from improper control of filename parameters used in PHP include/require statements, allowing attackers to include arbitrary local files from the server. This type of vulnerability (CWE-98) can potentially lead to sensitive information disclosure, configuration file exposure, or in some cases, remote code execution when combined with other attack vectors.

Critical Impact

Attackers can leverage this Local File Inclusion vulnerability to read sensitive files from the WordPress installation, potentially exposing database credentials, configuration data, and other critical system information.

Affected Products

• ThemeREX Nuts WordPress Theme version 1.10 and earlier
• All installations using Nuts theme from n/a through version 1.10

Discovery Timeline

• 2026-03-05 - CVE CVE-2026-28023 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-28023

Vulnerability Analysis

This vulnerability falls under CWE-98 (Improper Control of Filename for Include/Require Statement in PHP Program). The ThemeREX Nuts theme fails to properly sanitize user-controlled input before using it in PHP file inclusion functions. When an attacker can influence the filename parameter passed to include(), require(), include_once(), or require_once() functions, they can traverse the directory structure and include arbitrary files from the local filesystem.

Local File Inclusion vulnerabilities in WordPress themes are particularly dangerous because they can expose sensitive WordPress configuration files such as wp-config.php, which contains database credentials and authentication keys. Additionally, if log files or uploaded files can be included, attackers may achieve code execution by injecting PHP code into accessible files and then including them.

Root Cause

The root cause of this vulnerability is insufficient input validation and sanitization of user-supplied data before it is used in PHP file inclusion statements. The Nuts theme does not adequately restrict or filter filename parameters, allowing directory traversal sequences (such as ../) to be processed, enabling attackers to escape the intended directory and access files elsewhere on the server.

Attack Vector

An attacker can exploit this vulnerability by manipulating request parameters that are passed to PHP include functions within the theme. By crafting malicious requests containing directory traversal sequences, the attacker can include sensitive files from the server filesystem.

The exploitation typically involves:

1. Identifying the vulnerable parameter that controls file inclusion
2. Crafting a payload with directory traversal sequences (e.g., ../../../../etc/passwd or ../../../../wp-config.php)
3. Sending the malicious request to the vulnerable endpoint
4. Receiving the contents of the targeted file in the response or observing the effects of the included file

For detailed technical information about this vulnerability, refer to the Patchstack Vulnerability Report.

Detection Methods for CVE-2026-28023

Indicators of Compromise

• Unusual HTTP requests containing directory traversal patterns (../, ..%2f, %2e%2e/) targeting theme files
• Access logs showing requests to Nuts theme endpoints with suspicious path manipulation
• Unexpected file access attempts in system logs, particularly targeting sensitive configuration files
• Error logs indicating file inclusion failures with paths outside the theme directory

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block directory traversal patterns in request parameters
• Monitor access logs for requests containing encoded or unencoded path traversal sequences targeting the Nuts theme
• Deploy file integrity monitoring on sensitive configuration files like wp-config.php
• Utilize intrusion detection systems configured to alert on LFI attack signatures

Monitoring Recommendations

• Enable detailed logging for all requests to WordPress theme endpoints
• Set up alerts for repeated failed file access attempts or unusual file paths in error logs
• Monitor for any unauthorized access to sensitive WordPress files
• Implement real-time log analysis to detect LFI exploitation attempts

How to Mitigate CVE-2026-28023

Immediate Actions Required

• Update the ThemeREX Nuts theme to a patched version if available
• If no patch is available, consider temporarily disabling or replacing the vulnerable theme
• Implement WAF rules to block directory traversal attacks targeting the theme
• Review access logs for any signs of prior exploitation

Patch Information

Users should check for available updates from ThemeREX for the Nuts theme. Consult the Patchstack Vulnerability Report for the latest remediation guidance. If running version 1.10 or earlier, prioritize updating to a patched version as soon as one becomes available.

Workarounds

• Implement strict input validation at the server or WAF level to reject requests containing directory traversal patterns
• Use WordPress security plugins that provide virtual patching capabilities for known vulnerabilities
• Restrict file permissions on sensitive configuration files to limit the impact of potential LFI exploitation
• Consider switching to an alternative WordPress theme until a patch is released

# Example WAF rule configuration to block directory traversal (ModSecurity)
SecRule REQUEST_URI|ARGS|ARGS_NAMES "@rx (\.\.\/|\.\.\\|%2e%2e%2f|%252e%252e%252f)" \
    "id:100001,phase:2,deny,status:403,log,msg:'Directory Traversal Attempt Blocked'"