Attack Chain

1. Attacker authenticates to the Brave CMS application as a user with upload privileges.
2. The attacker navigates to a page or functionality within the CMS that utilizes the CKEditor for content creation or editing.
3. The attacker uses the CKEditor’s upload functionality to upload a malicious PHP script disguised as a legitimate file type (e.g., image).
4. The ckupload method in app/Http/Controllers/Dashboard/CkEditorController.php processes the uploaded file without proper validation of the file type or content.
5. The malicious PHP script is stored on the server in a publicly accessible directory.
6. The attacker crafts a request to directly access the uploaded PHP script via its URL.
7. The web server executes the PHP script, granting the attacker the ability to run arbitrary commands on the server.
8. The attacker establishes persistence, installs a web shell, and performs lateral movement within the network, escalating privileges as needed to achieve their objectives.

Impact

Successful exploitation of this vulnerability allows an attacker to execute arbitrary PHP code on the affected Brave CMS server. This can lead to complete compromise of the CMS instance, including unauthorized access to sensitive data, modification of website content, and potential lateral movement to other systems on the network. The CVSS v3.1 base score for this vulnerability is 8.8, indicating a high severity level. Organizations running vulnerable versions of Brave CMS are at risk of data breaches, website defacement, and further exploitation of their infrastructure.

Recommendation

• Upgrade Brave CMS to version 2.0.6 or later to remediate the unrestricted file upload vulnerability (CVE-2026-35164).
• Implement server-side file validation to prevent the upload of malicious files, regardless of file extension.
• Monitor web server logs for suspicious activity related to file uploads and execution of PHP scripts.
• Deploy the following Sigma rule to detect attempts to access potentially malicious PHP files in the web server’s upload directories.