CVE-2026-34787: Emlog Local File Inclusion Vulnerability

CVE-2026-34787 Overview

A Local File Inclusion (LFI) vulnerability has been identified in Emlog, an open source website building system. The vulnerability exists in admin/plugin.php at line 80, where the $plugin parameter from GET requests is directly used in a require_once path without proper sanitization. If the CSRF token check can be bypassed, an attacker with administrative privileges can include arbitrary PHP files from the server filesystem, potentially leading to remote code execution.

Critical Impact

Successful exploitation allows attackers to include arbitrary PHP files from the server filesystem, enabling code execution and potential complete server compromise.

Affected Products

• Emlog version 2.6.2 and prior versions
• Emlog open source website building system (all releases up to and including 2.6.2)

Discovery Timeline

• 2026-04-03 - CVE-2026-34787 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2026-34787

Vulnerability Analysis

This vulnerability is classified as CWE-98 (Improper Control of Filename for Include/Require Statement in PHP Program). The flaw resides in the administrative plugin management functionality where user-controlled input is passed directly to a file inclusion function without adequate validation or sanitization.

The vulnerability requires administrative privileges to exploit, as it exists within the admin panel. However, if an attacker can bypass the CSRF token protection mechanism—either through a separate vulnerability or social engineering—they can leverage this LFI to include malicious PHP files already present on the server or uploaded through other means.

The attack surface is network-accessible, requiring no user interaction beyond the initial authentication. The potential impact includes high confidentiality and integrity breaches, as successful exploitation grants the attacker the ability to execute arbitrary PHP code within the context of the web application.

Root Cause

The root cause is improper input validation in the admin/plugin.php file. The $plugin parameter received from GET requests is directly concatenated into a file path used by require_once without sanitization or validation against a whitelist of allowed values. This allows path traversal sequences and arbitrary file paths to be injected, enabling inclusion of unintended files from the server filesystem.

Attack Vector

The attack leverages the network-accessible administrative interface. An authenticated attacker with high privileges can craft a malicious GET request to admin/plugin.php with a specially crafted $plugin parameter containing path traversal sequences (e.g., ../) to navigate outside the intended directory and include arbitrary PHP files.

The attacker must either possess valid administrative credentials or find a way to bypass the CSRF token validation. Once the CSRF protection is circumvented, the attacker can manipulate the file inclusion path to execute arbitrary PHP code, potentially leveraging log poisoning, uploaded files, or other PHP files present on the system.

Detection Methods for CVE-2026-34787

Indicators of Compromise

• Unusual GET requests to admin/plugin.php containing path traversal sequences such as ../ or encoded variants
• Web server logs showing access to admin/plugin.php with abnormally long or suspicious plugin parameter values
• Unexpected file access patterns in PHP include paths, particularly accessing files outside the plugin directory
• Evidence of PHP file execution from non-standard directories such as /tmp, /var/log, or upload directories

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block path traversal patterns in the plugin parameter
• Monitor web server access logs for requests to admin/plugin.php with suspicious parameter values containing .., %2e%2e, or absolute paths
• Deploy file integrity monitoring on critical PHP files and directories to detect unauthorized modifications
• Enable PHP open_basedir restrictions and monitor for violation attempts

Monitoring Recommendations

• Audit administrative access logs for unusual login patterns or access from unexpected IP addresses
• Set up alerts for repeated failed CSRF token validation attempts which may indicate bypass attempts
• Monitor for new or modified PHP files in web-accessible directories that could be included via this vulnerability
• Review web server error logs for failed file inclusion attempts indicating reconnaissance activity

How to Mitigate CVE-2026-34787

Immediate Actions Required

• Restrict access to the Emlog administrative panel to trusted IP addresses only using firewall rules or .htaccess configurations
• Implement additional authentication layers such as HTTP Basic Authentication or VPN requirements for admin access
• Review and audit all administrative user accounts, removing any unnecessary or suspicious accounts
• Enable comprehensive logging for all administrative actions and file access attempts

Patch Information

At time of publication, there are no publicly available patches for this vulnerability. Administrators should monitor the GitHub Security Advisory for updates on official patches from the Emlog development team.

Workarounds

• Implement input validation at the web server level using ModSecurity or similar WAF to block path traversal attempts in the plugin parameter
• Apply PHP open_basedir restrictions to limit which directories can be accessed by PHP include functions
• Consider temporarily disabling the plugin management functionality if not actively needed by modifying access permissions on admin/plugin.php
• Deploy a reverse proxy with request filtering to sanitize incoming requests before they reach the Emlog application

# Apache .htaccess example to restrict admin access by IP
<Files "plugin.php">
    Order Deny,Allow
    Deny from all
    Allow from 192.168.1.0/24
    Allow from 10.0.0.0/8
</Files>