CVE-2026-1776: 
Ruby vulnerability analysis and mitigation

CVE-2026-1776 is a path traversal vulnerability in Camaleon CMS affecting versions 2.4.5.0 through 2.9.0 when configured to use the AWS S3 storage backend. The flaw exists in the download_private_file functionality of the CamaleonCmsAwsUploader class, which fails to validate file paths using the valid_folder_path? guard present in the local uploader implementation. This vulnerability represents a bypass of the incomplete fix for CVE-2024-46987 and allows any authenticated user — including low-privileged registered users — to read arbitrary files from the server's filesystem. It carries a CVSS v3.1 base score of 6.5 (Medium) (Feedly, VulnCheck).

The root cause is CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), where the CamaleonCmsAwsUploader backend's fetch_file, add_file, delete_folder, and delete_file methods accepted unsanitized user-supplied file paths without invoking the valid_folder_path? validation method that the local uploader correctly applies (GitHub Commit). An authenticated attacker can supply directory traversal sequences (e.g., ../../../etc/passwd) or URI-like paths (e.g., file:///etc/passwd) via the file parameter in the download_private_file endpoint, causing the application to read and return arbitrary files from the server filesystem (GitHub PR). Exploitation requires only a valid low-privileged user account and network access to the Camaleon CMS instance configured with the AWS S3 uploader backend (Feedly).

Successful exploitation allows any authenticated user to read arbitrary files from the web server's filesystem, including sensitive system files such as /etc/passwd, application configuration files, and potentially credentials or private keys stored on the server. The impact is limited to confidentiality — there is no integrity or availability impact — but exposure of configuration files or credentials could enable further lateral movement or privilege escalation within the environment. Only deployments using the AWS S3 (CamaleonCmsAwsUploader) backend are affected; installations using the local uploader are not vulnerable (Feedly, VulnCheck).

No public proof-of-concept exploit code is known to exist, and there is no evidence of active in-the-wild exploitation at this time (Feedly). The vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The EPSS score is approximately 0.072% (0.000720), indicating a low probability of exploitation in the near term. Exploitation does require authentication, which raises the bar compared to unauthenticated vulnerabilities, though any registered user account is sufficient (VulnCheck).

1. Reconnaissance: Identify Camaleon CMS instances (versions 2.4.5.0–2.9.0) configured with the AWS S3 uploader backend. This can be done by reviewing publicly accessible CMS login pages or application headers.
2. Obtain authentication: Register or obtain credentials for any low-privileged user account on the target Camaleon CMS instance.
3. Authenticate: Log in to the CMS using the obtained credentials to establish a valid session.
4. Craft traversal request: Send an authenticated HTTP request to the download_private_file endpoint, supplying a path traversal sequence in the file parameter, e.g., file=../../../etc/passwd or file=file:///etc/passwd.
5. Read arbitrary files: The application, lacking path validation in the AWS uploader backend, processes the traversal sequence and returns the contents of the targeted file, such as /etc/passwd or application configuration files containing credentials (GitHub Commit, VulnCheck).

• Network: Authenticated HTTP requests to the download_private_file endpoint containing path traversal sequences (../, ..%2F, file://, s3://) in the file parameter; unusual file download requests from low-privileged user accounts.
• Logs: Web server or Rails application logs showing requests to the private file download endpoint with parameters containing .., /etc/, or URI schemes (file://, https://); repeated access attempts to sensitive system paths from the same authenticated session.
• File System: No direct file system artifacts are created by read-only exploitation, but access to files outside the expected media/upload directories (e.g., /etc/passwd, application .env or database.yml) should be treated as suspicious.

The vulnerability is fixed in commit f54a77e (merged March 9, 2026 via PR #1127), which adds valid_folder_path? validation guards to the fetch_file, add_file, delete_folder, and delete_file methods in CamaleonCmsAwsUploader. Administrators should upgrade Camaleon CMS to any version incorporating commit f54a77e or later (GitHub Commit, GitHub PR). As an interim workaround if patching is not immediately possible, switch the storage backend from CamaleonCmsAwsUploader to the local uploader (which correctly validates paths), restrict CMS registration to trusted users only, and apply network-level access controls to limit exposure of the CMS instance (Feedly).

Red Hat has tracked this vulnerability in their security advisory database (Red Hat). VulnCheck published a dedicated advisory documenting the issue as an authenticated path traversal in the AWS uploader (VulnCheck). The vulnerability was also noted in a HackTheBox writeup published in June 2026, suggesting it has been incorporated into CTF/lab scenarios (0xdf Blog). No significant broader media coverage or notable researcher commentary beyond these sources has been identified.