CVE-2026-1776: Camaleon CMS Path Traversal Vulnerability

CVE-2026-1776 Overview

Camaleon CMS versions 2.4.5.0 through 2.9.0, prior to commit f54a77e, contain a path traversal vulnerability (CWE-22) in the AWS S3 uploader implementation. This security flaw allows authenticated users to read arbitrary files from the web server's filesystem. The vulnerability exists in the download_private_file functionality when the application is configured to use the CamaleonCmsAwsUploader backend.

Unlike the local uploader implementation, the AWS uploader does not validate file paths with the valid_folder_path? method, allowing directory traversal sequences to be supplied via the file parameter. This issue represents a bypass of the incomplete fix for CVE-2024-46987 and specifically affects deployments using the AWS S3 storage backend.

Critical Impact

Any authenticated user, including low-privileged registered users, can access sensitive system files such as /etc/passwd through directory traversal, potentially exposing credentials, configuration data, and other sensitive information.

Affected Products

• Camaleon CMS versions 2.4.5.0 through 2.9.0
• Deployments using the CamaleonCmsAwsUploader backend
• Installations prior to commit f54a77e

Discovery Timeline

• 2026-03-10 - CVE-2026-1776 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2026-1776

Vulnerability Analysis

This path traversal vulnerability stems from inconsistent security controls between different storage backends in Camaleon CMS. While the local file uploader implementation properly validates file paths using the valid_folder_path? method to prevent directory traversal attacks, the AWS S3 uploader (CamaleonCmsAwsUploader) lacks this same validation.

When processing file download requests through the download_private_file functionality, the application accepts a file parameter that specifies which file to retrieve. An attacker can craft malicious requests containing directory traversal sequences (such as ../) to escape the intended file storage directory and access arbitrary files on the server's filesystem.

This vulnerability is particularly notable as it represents a bypass of a previous security fix implemented for CVE-2024-46987. The original patch addressed path traversal in the local uploader but failed to apply equivalent protections to the AWS S3 uploader code path.

Root Cause

The root cause is missing input validation in the AWS S3 uploader implementation. The CamaleonCmsAwsUploader backend does not call the valid_folder_path? validation function when processing file paths in the download_private_file functionality. This inconsistency between storage backends created a security gap that allows authenticated users to supply directory traversal sequences in the file parameter without proper sanitization.

Attack Vector

The attack is network-based and requires only low-level authentication privileges. An attacker with a valid user account on a Camaleon CMS instance configured with AWS S3 storage can exploit this vulnerability by:

1. Authenticating to the Camaleon CMS application with any valid user account
2. Crafting a request to the download_private_file endpoint with directory traversal sequences in the file parameter (e.g., ../../../etc/passwd)
3. The AWS uploader processes the path without validation, allowing access to files outside the intended directory
4. The server returns the contents of the requested file to the attacker

The vulnerability is exploited by manipulating the file path parameter to include sequences like ../ which traverse up the directory structure. For example, an attacker could request a path such as ../../../etc/passwd to read the system password file. Technical implementation details and the security fix can be found in the GitHub Pull Request #1127 and the VulnCheck Advisory.

Detection Methods for CVE-2026-1776

Indicators of Compromise

• HTTP requests to file download endpoints containing directory traversal sequences such as ../, ..%2f, or ..%5c
• Unusual access patterns to the download_private_file endpoint from low-privileged user accounts
• Server logs showing requests for sensitive system files like /etc/passwd, /etc/shadow, or application configuration files
• Multiple file access attempts from the same authenticated session targeting different system paths

Detection Strategies

• Implement web application firewall (WAF) rules to detect and block directory traversal patterns in request parameters
• Configure intrusion detection systems (IDS) to alert on file path manipulation attempts in HTTP requests
• Monitor application logs for access attempts to system files outside the designated upload directories
• Deploy SentinelOne agents to detect and respond to file system access anomalies on web servers

Monitoring Recommendations

• Enable detailed logging for all file download operations in Camaleon CMS
• Set up alerts for any access to sensitive system paths through web application endpoints
• Monitor for authenticated users accessing an unusually high number of different file paths
• Implement file integrity monitoring on critical system configuration files

How to Mitigate CVE-2026-1776

Immediate Actions Required

• Upgrade Camaleon CMS to a version that includes commit f54a77e or later
• Review application logs for signs of exploitation attempts
• Audit user accounts with access to the CMS and remove unnecessary privileges
• Consider temporarily disabling the AWS S3 uploader backend until patching is complete

Patch Information

The vulnerability has been addressed in commit f54a77e2a7be601215ea1b396038c589a0cab9af. Organizations running affected versions should update immediately by pulling the latest code from the official GitHub repository. The fix adds proper path validation to the AWS S3 uploader to match the security controls already present in the local uploader implementation.

Workarounds

• If immediate patching is not possible, consider switching to the local file uploader backend which includes proper path validation
• Implement additional input validation at the web server or reverse proxy level to filter directory traversal sequences
• Restrict access to the file download functionality to trusted administrative users only
• Deploy a web application firewall (WAF) with rules to block path traversal attack patterns

# Example nginx configuration to block directory traversal attempts
location ~ /download_private_file {
    # Block requests containing directory traversal sequences
    if ($request_uri ~* "\.\.") {
        return 403;
    }
    # Additional security headers
    add_header X-Content-Type-Options nosniff;
    add_header X-Frame-Options DENY;
}