CVE-2026-14946: File Upload RCE Vulnerability

CVE-2026-14946 Overview

CVE-2026-14946 is an unrestricted file upload vulnerability [CWE-434] that allows a high-privileged remote attacker to upload a .php file and execute it by requesting it directly from /uploads/<filename>.php. The flaw stems from improper file type validation on the upload handler. Successful exploitation results in arbitrary code execution on the underlying host and can lead to full system compromise. The vulnerability is documented in the CERT-VDE Security Advisory VDE-2026-078.

Critical Impact
An authenticated attacker with high privileges can achieve arbitrary code execution and full system compromise by uploading and directly requesting a malicious PHP file.

Affected Products

Refer to the CERT-VDE Security Advisory VDE-2026-078 for the authoritative list of affected products
Affected product identifiers are not enumerated in the current NVD entry
Vendor and CPE data pending publication in NVD

Discovery Timeline

2026-08-20 - CVE-2026-14946 published to NVD
2026-08-20 - Last updated in NVD database

Technical Details for CVE-2026-14946

Vulnerability Analysis

The vulnerability is a classic unrestricted upload of file with dangerous type flaw [CWE-434]. The application accepts a file upload from an authenticated, high-privileged user and writes the file to the web-accessible /uploads/ directory without validating the file's type, extension, or content. Because the upload directory sits within the PHP interpreter's execution scope, requesting the uploaded file directly causes the server to execute its contents as PHP.

The attacker requires network access and authenticated high privileges. User interaction is not needed. Once the file is placed on disk, invoking it via HTTP yields code execution in the context of the web server process.

Root Cause

The upload handler does not enforce a server-side allowlist of permitted file extensions or MIME types. It also fails to strip executable extensions, rename uploaded files, or store them outside the web root. Any of these controls would break the attack chain.

Attack Vector

The attacker authenticates to the application with a high-privileged account, submits a POST request containing a PHP payload with a .php extension to the file upload endpoint, and then issues a GET request to /uploads/<filename>.php. The server interprets the file and executes attacker-controlled code. Refer to the CERT-VDE Security Advisory for the technical description of the affected endpoints.

Detection Methods for CVE-2026-14946

Indicators of Compromise

Presence of unexpected .php, .phtml, or .phar files within the /uploads/ directory or any web-accessible upload path
HTTP POST requests to file upload endpoints followed by GET requests to /uploads/*.php from the same client
Web server process spawning shell interpreters such as sh, bash, cmd.exe, or powershell.exe
Outbound network connections initiated by the web server process to unfamiliar destinations

Detection Strategies

Alert on write operations that create files with executable script extensions inside upload directories
Correlate authenticated upload actions with subsequent direct requests to the uploaded filename
Inspect uploaded file magic bytes and compare against declared MIME types to identify polyglot or masqueraded payloads

Monitoring Recommendations

Enable verbose web access logging and forward logs to a centralized analytics platform for retention and correlation
Monitor process ancestry for the web server user to detect anomalous child processes indicating post-exploitation activity
Track file integrity on web root and upload directories, flagging new script files for immediate review

How to Mitigate CVE-2026-14946

Immediate Actions Required

Apply the vendor-supplied patch referenced in the CERT-VDE Security Advisory VDE-2026-078 as soon as it is available
Restrict administrative and high-privileged accounts to trusted operators and enforce multi-factor authentication on those accounts
Audit the /uploads/ directory for unexpected script files and remove any unauthorized content

Patch Information

Consult the CERT-VDE Security Advisory VDE-2026-078 for vendor-issued patch details and fixed version numbers. Apply the update in a controlled maintenance window and verify the upload endpoint enforces server-side extension and content validation after patching.

Workarounds

Configure the web server to disable PHP execution within the /uploads/ directory using directives such as php_flag engine off or an equivalent handler override
Deploy a web application firewall rule that blocks uploads of files with .php, .phtml, .phar, or double-extension patterns
Relocate the upload storage location outside the web-accessible document root and serve files through a controlled download handler
Restrict network access to the management interface hosting the upload functionality to trusted administrative networks only

bash

# Apache: disable PHP execution in the uploads directory
<Directory "/var/www/html/uploads">
    php_flag engine off
    RemoveHandler .php .phtml .phar
    RemoveType .php .phtml .phar
    AddType text/plain .php .phtml .phar
</Directory>

# Nginx: return 403 for any script execution attempts in uploads
location ^~ /uploads/ {
    location ~* \.(php|phtml|phar)$ {
        deny all;
        return 403;
    }
}