CVE-2026-28515: openDCIM Auth Bypass Vulnerability

CVE-2026-28515 Overview

CVE-2026-28515 is a critical missing authorization vulnerability in openDCIM version 23.04, through commit 4467e9c4. The vulnerability exists in install.php and container-install.php, where the installer and upgrade handler expose LDAP configuration functionality without enforcing application role checks. This allows any authenticated user to access sensitive configuration functionality regardless of their assigned privileges. In deployments where REMOTE_USER is set without authentication enforcement, the endpoint may be accessible without any credentials, enabling unauthorized modification of application configuration.

Critical Impact

Unauthenticated or low-privileged attackers can modify critical LDAP and application configuration settings, potentially leading to complete application compromise, authentication bypass, or privilege escalation.

Affected Products

• openDCIM version 23.04 (through commit 4467e9c4)
• openDCIM installations using install.php for configuration
• openDCIM deployments using container-install.php

Discovery Timeline

• 2026-02-27 - CVE-2026-28515 published to NVD
• 2026-03-02 - Last updated in NVD database

Technical Details for CVE-2026-28515

Vulnerability Analysis

This vulnerability is classified as CWE-862 (Missing Authorization). The core issue stems from the installer and container installation scripts (install.php and container-install.php) failing to implement proper authorization checks before allowing access to LDAP configuration functionality. When an application relies solely on authentication without proper authorization controls, any authenticated user—regardless of their role or privilege level—can access administrative functions that should be restricted.

The impact is particularly severe in environments where the REMOTE_USER environment variable is set without proper authentication enforcement at the web server level. In such configurations, an attacker may not need any credentials at all to access and modify critical application settings, including LDAP configuration parameters that control how users authenticate to the system.

Root Cause

The root cause is the absence of role-based access control (RBAC) checks in the install.php and container-install.php files. These scripts expose sensitive LDAP configuration endpoints without verifying whether the requesting user has administrative privileges. The vulnerable code paths at lines 420-434 in install.php and lines 421-435 in container-install.php process configuration changes without proper authorization gates. This represents a fundamental design flaw where installation/upgrade functionality remains accessible after initial deployment without appropriate access restrictions.

Attack Vector

The vulnerability is exploitable over the network with low attack complexity. An attacker can directly access the vulnerable endpoints through standard HTTP requests. The attack does not require user interaction and can be performed by:

1. Any authenticated user with minimal privileges accessing install.php or container-install.php
2. Unauthenticated users in environments where REMOTE_USER authentication is misconfigured
3. Attackers who can modify LDAP settings to redirect authentication to a malicious LDAP server they control

The vulnerability mechanism involves sending crafted HTTP requests to the installer endpoints. When these requests reach the LDAP configuration handlers, the application processes them without validating whether the user has administrative authority. This allows modification of authentication settings, potentially enabling the attacker to create backdoor accounts or redirect authentication flows. For detailed technical analysis and exploitation methodology, see the Chocapikk SQLi to RCE Post and the associated exploit repository.

Detection Methods for CVE-2026-28515

Indicators of Compromise

• Unexpected HTTP requests to /install.php or /container-install.php from non-administrative IP addresses
• Modifications to LDAP configuration settings without corresponding administrator activity
• Authentication failures following unauthorized configuration changes
• Web server access logs showing POST requests to installation scripts with LDAP-related parameters

Detection Strategies

• Monitor web application logs for access attempts to install.php and container-install.php endpoints, especially from users without administrative roles
• Implement file integrity monitoring on openDCIM configuration files to detect unauthorized LDAP setting changes
• Configure web application firewalls (WAF) to alert on or block requests to installation endpoints in production environments
• Review authentication logs for anomalous patterns that may indicate LDAP configuration tampering

Monitoring Recommendations

• Enable verbose logging for the openDCIM application and correlate with web server access logs
• Set up alerts for any access to installation scripts after initial deployment is complete
• Monitor for changes to LDAP server addresses, bind credentials, or authentication parameters in the application database
• Implement network-level monitoring for unexpected outbound connections to LDAP ports (389, 636)

How to Mitigate CVE-2026-28515

Immediate Actions Required

• Restrict access to install.php and container-install.php at the web server level using authentication and IP-based access controls
• Review and audit current LDAP configuration settings for any unauthorized modifications
• Ensure REMOTE_USER authentication is properly enforced at the web server level and not blindly trusted by the application
• Apply the security patch from Pull Request #1664 as soon as possible

Patch Information

The openDCIM maintainers have addressed this vulnerability in Pull Request #1664. The patch introduces proper authorization checks to ensure only users with administrative privileges can access LDAP configuration functionality in the installer and container installation scripts. The specific code changes can be reviewed in the PR commit changes. Organizations should update to the patched version immediately. For additional details, refer to the VulnCheck advisory.

Workarounds

• Remove or rename install.php and container-install.php files after initial installation is complete
• Implement web server-level access controls (e.g., Apache .htaccess or Nginx location blocks) to restrict access to installation scripts
• Configure network segmentation to limit access to the openDCIM administrative interface to trusted management networks only

# Apache configuration example - restrict access to install scripts
<FilesMatch "^(install|container-install)\.php$">
    Require ip 10.0.0.0/8
    Require ip 192.168.0.0/16
    # Or deny all access after installation:
    # Require all denied
</FilesMatch>