CVE-2025-8265: 299Ko CMS 2.0.0 RCE Vulnerability

CVE-2025-8265 Overview

CVE-2025-8265 is an unrestricted file upload vulnerability in 299Ko CMS 2.0.0. The flaw resides in the /admin/filemanager/view endpoint within the File Management component. An authenticated attacker with high privileges can upload arbitrary files remotely, leading to limited impact on confidentiality, integrity, and availability. The exploit has been publicly disclosed. The vendor was contacted before public disclosure but did not respond. The weakness is categorized under CWE-284: Improper Access Control.

Critical Impact
A public proof-of-concept exists for an unrestricted file upload in the 299Ko CMS admin file manager, enabling authenticated attackers to place arbitrary files on the server.

Affected Products

299Ko CMS 2.0.0
Component: /admin/filemanager/view (File Management)
Deployment scenarios exposing the admin panel to remote users

Discovery Timeline

2025-07-28 - CVE-2025-8265 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-8265

Vulnerability Analysis

The vulnerability exists in the file management view of the 299Ko CMS 2.0.0 administrative backend. The /admin/filemanager/view handler does not properly restrict which file types an authenticated administrator can upload. This missing validation permits attackers to place arbitrary content, including server-executable scripts, into web-accessible directories.

Exploitation requires network access to the admin interface and valid high-privilege credentials. Because the affected functionality is intended for administrators, the attack surface depends on the exposure of the admin panel and the strength of administrator authentication. Once a malicious file is written, an attacker can attempt to trigger it through the web server, potentially escalating impact beyond the base scoring.

Root Cause

The root cause is improper access control ([CWE-284]) around the file upload flow. The application relies on the administrative role for authorization but does not enforce restrictions on uploaded file extensions, MIME types, or content. This allows any authenticated administrator to write arbitrary files to the server file system through the file manager.

Attack Vector

Attackers deliver the exploit over the network by submitting crafted upload requests to /admin/filemanager/view after authenticating to the admin panel. No user interaction is required beyond the attacker's own session. Public disclosure of the exploit lowers the barrier for opportunistic abuse of exposed 299Ko installations.

The vulnerability is documented in the proof-of-concept PDF on GitHub and tracked at VulDB entry #317853. No verified exploit code snippet is reproduced here.

Detection Methods for CVE-2025-8265

Indicators of Compromise

Unexpected files with executable extensions (.php, .phtml, .phar) written to directories managed by the 299Ko file manager
HTTP POST requests to /admin/filemanager/view containing multipart uploads of non-standard file types
New or modified files in web-accessible paths with recent timestamps that do not correlate with legitimate administrator activity
Outbound connections initiated from the web server process shortly after admin file manager activity

Detection Strategies

Monitor web server access logs for POST traffic to /admin/filemanager/view and correlate with the authenticated user
Alert on file writes under the 299Ko document root that produce script extensions or unknown binaries
Baseline legitimate administrator upload behavior and flag deviations in file type, size, or frequency

Monitoring Recommendations

Enable file integrity monitoring on the 299Ko installation directory and upload paths
Forward web server and application logs to a centralized platform for correlation with authentication events
Track failed and successful admin logins to detect credential abuse preceding upload activity

How to Mitigate CVE-2025-8265

Immediate Actions Required

Restrict access to the 299Ko admin interface using network controls, VPN, or IP allowlists
Rotate all administrator credentials and enforce strong, unique passwords with multi-factor authentication where possible
Audit the file manager directories for unauthorized files and remove any suspicious artifacts
Review web server configuration to disable script execution in upload directories

Patch Information

At the time of publication, no vendor patch has been released. The vendor was contacted before disclosure but did not respond according to the VulDB submission. Monitor the 299Ko project repository for future updates and apply any released fixes promptly.

Workarounds

Remove or restrict the /admin/filemanager/view endpoint at the web server or reverse proxy level if the file manager is not required
Configure the web server to refuse execution of PHP or other server-side scripts in user-writable directories
Place the admin panel behind an authenticating reverse proxy to add an additional access control layer
Consider migrating to a maintained CMS if no vendor response is forthcoming

bash

# Example nginx configuration to block script execution in an upload directory
location ^~ /uploads/ {
    location ~ \.(php|phtml|phar|pl|py|jsp|cgi)$ {
        deny all;
        return 403;
    }
}

# Restrict admin panel access to a trusted network
location /admin/ {
    allow 10.0.0.0/8;
    deny all;
}