CVE-2026-5482: Responsive FileManager RCE Vulnerability

CVE-2026-5482 Overview

CVE-2026-5482 is an unrestricted file upload vulnerability [CWE-434] in Responsive FileManager version 9.14.0. The dialog.php endpoint accepts file uploads without authentication and without validating file type or extension. An unauthenticated remote attacker can upload executable PHP files to the web server, resulting in Remote Code Execution (RCE). The project is unmaintained at the time of CVE assignment, so no official patch is expected. The vulnerability was published to NVD on 2026-06-15 and last modified on 2026-06-17.

Critical Impact
Unauthenticated attackers can upload arbitrary files to vulnerable Responsive FileManager 9.14.0 installations through dialog.php and execute code on the underlying server.

Affected Products

Responsive FileManager 9.14.0 (latest release at time of disclosure)
Web applications bundling Responsive FileManager as a file management component
The upstream project is unmaintained, so all earlier versions should be considered potentially affected

Discovery Timeline

2026-06-15 - CVE-2026-5482 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2026-5482

Vulnerability Analysis

Responsive FileManager is a PHP-based file management library used to provide upload, browse, and edit functionality inside web applications and CMS integrations. The dialog.php endpoint exposes upload handling to clients. In version 9.14.0 this endpoint does not require authentication and does not enforce extension or MIME allow-listing on the uploaded file.

An attacker can submit a multipart POST request to dialog.php carrying a PHP payload with an executable extension. The server writes the file to a directory served by the web application. The attacker then requests the uploaded file directly to execute arbitrary PHP code in the context of the web server user.

This results in full compromise of the application: arbitrary command execution, lateral movement on the host, data exfiltration, and persistence through web shells. Because the project is unmaintained, integrators must remove the component or apply external controls. See the CERT Poland advisory for CVE-2026-5482 for additional context.

Root Cause

The root cause is the absence of authentication on the dialog.php upload handler combined with missing server-side validation of the uploaded file extension and content type. The CWE classification is [CWE-434] Unrestricted Upload of File with Dangerous Type. The handler trusts client-supplied filenames and writes the file into a web-accessible directory without enforcing an allow-list of safe extensions.

Attack Vector

The attack vector is network-based and requires no privileges or user interaction. An attacker locates a reachable dialog.php endpoint, sends a crafted multipart upload containing a PHP file, and then issues a GET request to the resulting path. The uploaded script executes with the privileges of the PHP runtime, granting an interactive foothold on the host.

No verified public proof-of-concept code is referenced in the advisory. Technical details are documented in the Responsive FileManager GitHub repository and the CERT Poland advisory.

Detection Methods for CVE-2026-5482

Indicators of Compromise

HTTP POST requests to dialog.php from unauthenticated sources, particularly with multipart bodies containing files with extensions such as .php, .phtml, .phar, or double extensions like .jpg.php
New files in upload directories (commonly source/, uploads/, or configured upload_dir) with PHP-executable extensions or unexpected timestamps
Outbound network connections originating from the web server process to attacker-controlled hosts following an upload event
Web server logs showing GET requests to recently uploaded files in the file manager upload path

Detection Strategies

Inspect web server access logs for POST requests to dialog.php and correlate them with subsequent GET requests to files in upload directories
Deploy file integrity monitoring on Responsive FileManager upload directories to alert on the creation of files with server-executable extensions
Use a web application firewall rule to flag multipart uploads containing <?php, <?=, or shell-related strings in the request body

Monitoring Recommendations

Alert on PHP processes spawning shell interpreters (sh, bash, cmd.exe) or system utilities such as wget, curl, nc, or whoami
Monitor for new PHP files written by the web server user account outside of normal deployment workflows
Track egress traffic from web servers to unfamiliar destinations, which often indicates reverse shells or staged tooling

How to Mitigate CVE-2026-5482

Immediate Actions Required

Remove or disable the Responsive FileManager component from production applications, since the project is unmaintained and no vendor patch is available
Block external access to the dialog.php endpoint at the reverse proxy or web application firewall until the component is removed
Audit upload directories for unauthorized PHP, phtml, or phar files and remove any identified web shells
Rotate credentials and secrets stored on or accessible from the affected web server, assuming potential compromise

Patch Information

No official patch is available. The Responsive FileManager project on GitHub is unmaintained as of the CVE assignment. Operators should migrate to an actively maintained file management library or implement compensating controls described below.

Workarounds

Restrict execution of PHP in upload directories by configuring the web server, for example denying .php handler mapping under the upload path in Apache or Nginx
Enforce authentication in front of dialog.php using reverse proxy access controls, IP allow-listing, or HTTP basic auth
Apply server-side allow-listing of file extensions and validate MIME type using a WAF rule when the component cannot be removed immediately
Run the web server process with least privilege and isolate it using filesystem permissions or containerization to limit blast radius

bash

# Nginx configuration to deny PHP execution in Responsive FileManager upload directory
location ~* ^/path/to/responsivefilemanager/source/.*\.(php|phtml|phar)$ {
    deny all;
    return 403;
}

# Block external access to the vulnerable endpoint
location = /path/to/responsivefilemanager/dialog.php {
    deny all;
    return 403;
}