CVE-2026-27894: LDAP Account Manager (LAM) RCE Vulnerability

CVE-2026-27894 Overview

LDAP Account Manager (LAM) is a web-based frontend for managing entries stored in an LDAP directory, including users, groups, and DHCP settings. A Local File Inclusion (LFI) vulnerability was discovered in the PDF export functionality that allows authenticated users to include local PHP files and execute arbitrary code on the server. When chained with the related vulnerability GHSA-88hf-2cjm-m9g8, this flaw enables full remote code execution capabilities.

Critical Impact

Authenticated attackers can achieve remote code execution by exploiting the PDF export feature to include and execute arbitrary local PHP files, potentially leading to complete server compromise.

Affected Products

• LDAP Account Manager (LAM) versions prior to 9.5

Discovery Timeline

• 2026-03-18 - CVE CVE-2026-27894 published to NVD
• 2026-03-18 - Last updated in NVD database

Technical Details for CVE-2026-27894

Vulnerability Analysis

This vulnerability is classified as CWE-98: Improper Control of Filename for Include/Require Statement in PHP Program, commonly known as Local File Inclusion (LFI). The flaw exists within the PDF export functionality of LDAP Account Manager, where user-controlled input is improperly sanitized before being used in a PHP include statement. An authenticated user can manipulate the PDF export parameters to include arbitrary local PHP files from the server's filesystem.

The attack requires network access and valid authentication credentials to the LAM interface. Once authenticated, an attacker can craft malicious requests to the PDF export feature that reference local PHP files. When combined with the companion vulnerability documented in GHSA-88hf-2cjm-m9g8, attackers can upload or create malicious PHP content and then include it through this LFI vulnerability, achieving arbitrary code execution on the underlying server.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and sanitization in the PDF export functionality. The application fails to properly validate file paths provided by users before including them in PHP include statements. This allows directory traversal sequences and references to arbitrary local files, enabling attackers to include PHP files outside the intended directory scope.

Attack Vector

The attack is conducted over the network by authenticated users through the web interface. An attacker must first authenticate to the LDAP Account Manager application, then navigate to the PDF export functionality. By manipulating the parameters associated with PDF profile files, the attacker can inject path traversal sequences or direct file references to include local PHP files. The included PHP code is then executed in the context of the web server process, granting the attacker the same privileges as the web server user.

The vulnerability mechanism involves manipulating PDF profile file references in the export functionality. When processing PDF export requests, the application uses user-supplied input to construct file paths for PHP include statements. Without proper sanitization, an attacker can traverse the directory structure to include arbitrary PHP files, such as configuration files that may have been manipulated through companion vulnerabilities or other writable locations on the server. For detailed technical information, refer to the GitHub Security Advisory GHSA-w7xq-vjr3-p9cf.

Detection Methods for CVE-2026-27894

Indicators of Compromise

• Unusual requests to PDF export endpoints containing path traversal sequences such as ../ or absolute file paths
• Web server logs showing access to PDF export functionality with unexpected file parameters
• PHP error logs indicating file inclusion attempts for files outside the expected PDF profile directory
• Unexpected process execution or network connections originating from the web server process

Detection Strategies

• Monitor web application logs for requests to LAM PDF export endpoints containing suspicious path traversal patterns
• Implement web application firewall (WAF) rules to detect and block LFI attack patterns in request parameters
• Review web server access logs for authenticated sessions making unusual sequences of requests to export functionality
• Configure intrusion detection systems to alert on PHP file inclusion attempts outside expected directories

Monitoring Recommendations

• Enable verbose logging for the LDAP Account Manager application to capture all PDF export requests
• Monitor file system access patterns for the web server user, particularly reads of PHP files outside the LAM application directory
• Implement real-time alerting for any process spawning or network connections initiated by the web server process
• Regularly audit the /var/lib/ldap-account-manager/config directory for unauthorized modifications

How to Mitigate CVE-2026-27894

Immediate Actions Required

• Upgrade LDAP Account Manager to version 9.5 or later immediately
• If immediate upgrade is not possible, implement the workaround by making /var/lib/ldap-account-manager/config read-only for the web-server user
• Delete existing PDF profile files to prevent exploitation (note: this disables PDF export functionality)
• Review authentication logs for signs of compromise and audit any accounts that accessed PDF export features

Patch Information

The vulnerability has been fixed in LDAP Account Manager version 9.5. Users should upgrade to this version or later to receive the security fix. The patch release is available from the GitHub Release 9.5 page. Additionally, users should review the related security advisory GHSA-88hf-2cjm-m9g8 and ensure patches for both vulnerabilities are applied to prevent exploitation chains.

Workarounds

• Make the /var/lib/ldap-account-manager/config directory read-only for the web-server user to prevent file manipulation
• Delete PDF profile files from the configuration directory (disables PDF export functionality until upgrade)
• Implement network segmentation to limit access to the LAM interface to trusted networks only
• Enable additional authentication factors for LAM administrative access to reduce the risk of credential compromise

# Configuration example
# Make config directory read-only for web server user
chmod -R a-w /var/lib/ldap-account-manager/config

# Remove PDF profile files to disable PDF export
rm -f /var/lib/ldap-account-manager/config/*.pdf

# Verify permissions
ls -la /var/lib/ldap-account-manager/config/