CVE-2026-27991: Avventure Path Traversal Vulnerability

CVE-2026-27991 Overview

CVE-2026-27991 is a PHP Local File Inclusion (LFI) vulnerability affecting the ThemeREX Avventure WordPress theme. The vulnerability stems from improper control of filename for include/require statements in the PHP program, allowing attackers to include local files from the server. This can potentially lead to sensitive information disclosure, remote code execution, or full system compromise depending on the server configuration and accessible files.

Critical Impact

Attackers can exploit this vulnerability to include arbitrary local files on the web server, potentially exposing sensitive configuration files, credentials, or achieving code execution through log poisoning techniques.

Affected Products

• ThemeREX Avventure WordPress Theme versions through 1.1.12
• WordPress installations using the vulnerable Avventure theme

Discovery Timeline

• 2026-03-05 - CVE CVE-2026-27991 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-27991

Vulnerability Analysis

This vulnerability is classified under CWE-98 (Improper Control of Filename for Include/Require Statement in PHP Program). The ThemeREX Avventure theme fails to properly sanitize user-controlled input before using it in PHP include or require statements. This allows an attacker to manipulate file path parameters to include arbitrary local files from the server filesystem.

Local File Inclusion vulnerabilities in WordPress themes are particularly dangerous as they can provide attackers access to the wp-config.php file containing database credentials, authentication keys, and other sensitive configuration data. Additionally, if the server allows file uploads or maintains accessible log files, attackers can chain this vulnerability with log poisoning techniques to achieve remote code execution.

Root Cause

The root cause of this vulnerability lies in insufficient input validation within the Avventure theme's file inclusion logic. The theme accepts user-controlled parameters that are directly passed to PHP include(), require(), include_once(), or require_once() functions without adequate sanitization or path restriction. This allows directory traversal sequences (such as ../) to escape the intended directory context and access files elsewhere on the filesystem.

Attack Vector

An attacker can exploit this vulnerability by sending specially crafted requests to the WordPress site containing manipulated file path parameters. The attack typically involves:

1. Identifying vulnerable endpoints in the Avventure theme that accept file path input
2. Crafting malicious requests with directory traversal sequences to reach target files
3. Including sensitive local files such as /etc/passwd, wp-config.php, or log files
4. Potentially escalating to remote code execution through log poisoning or inclusion of uploaded files

The vulnerability can be exploited remotely without authentication, making it particularly dangerous for publicly accessible WordPress installations. For detailed technical information, refer to the Patchstack Vulnerability Report.

Detection Methods for CVE-2026-27991

Indicators of Compromise

• Unusual HTTP requests containing directory traversal patterns (../, ..%2f, ....//) targeting theme files
• Web server logs showing attempts to access sensitive files like wp-config.php, /etc/passwd, or /proc/self/environ
• Requests with null byte injection attempts (%00) to bypass file extension restrictions
• Unexpected access patterns to theme endpoints with file path parameters

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block Local File Inclusion attack patterns
• Monitor web server access logs for directory traversal sequences in URL parameters and POST data
• Implement file integrity monitoring on WordPress core files and configuration files
• Use WordPress security plugins that can detect suspicious file inclusion attempts

Monitoring Recommendations

• Enable verbose logging for the WordPress installation and web server to capture full request details
• Configure alerting for any access attempts to sensitive system files via web requests
• Regularly review web application logs for anomalous patterns indicating exploitation attempts
• Monitor for unusual file read operations by the web server process

How to Mitigate CVE-2026-27991

Immediate Actions Required

• Update the ThemeREX Avventure theme to a patched version if available from the vendor
• If no patch is available, consider temporarily deactivating the Avventure theme and switching to a secure alternative
• Implement WAF rules to block Local File Inclusion attack patterns targeting your WordPress installation
• Restrict filesystem permissions to limit web server access to only necessary files
• Remove or restrict access to sensitive files that could be targeted via LFI

Patch Information

Users should check with ThemeREX for an updated version of the Avventure theme that addresses this vulnerability. Until a patch is available, implementing the workarounds below is strongly recommended. Refer to the Patchstack Vulnerability Report for the latest patch status and updates.

Workarounds

• Deploy a Web Application Firewall with rules configured to block LFI attack patterns including directory traversal sequences
• Implement PHP open_basedir restrictions to limit file access to the WordPress installation directory
• Disable dangerous PHP functions like include() and require() for user-controlled input through custom security hardening
• Consider switching to an alternative WordPress theme until a security patch is released

# Configuration example - PHP open_basedir restriction in php.ini or .htaccess
# Restrict PHP file operations to the WordPress directory
php_admin_value open_basedir "/var/www/html/wordpress:/tmp"

# Apache mod_security rule to block common LFI patterns
SecRule REQUEST_URI "@rx \.\./" "id:1001,phase:1,deny,status:403,msg:'Directory Traversal Attempt'"
SecRule ARGS "@rx \.\./" "id:1002,phase:2,deny,status:403,msg:'LFI Attack Detected'"