CVE-2026-9182

Executive Summary

CVE-2026-9182 is an unrestricted file upload vulnerability in ArcGIS Server. An unauthenticated attacker can upload arbitrary files to the server, potentially leading to remote code execution, data exfiltration, or server compromise. The vulnerability has a CVSS score of 5.3 (Medium) and an EPSS score of 0.0%, indicating low exploitation probability at this time. No public exploit code or proof-of-concept is available, but the risk remains significant due to the lack of authentication requirements.

Note: This vulnerability is specific to the ArcGIS Server ecosystem and is not related to any web server software such as Apache or Nginx.

CVSS Breakdown & Threat Level

• CVSS Score: 5.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: Low
• Availability Impact: None

The low EPSS score (0.0%) suggests that exploitation is not currently widespread, but the lack of authentication and the potential for arbitrary file upload make this a high-priority vulnerability for patching and monitoring.

Deep Dive & Mechanics

The vulnerability resides in an unspecified endpoint of ArcGIS Server that handles file uploads. The server fails to validate the file type, size, or content before storing the uploaded file. An unauthenticated attacker can send a crafted HTTP request containing a malicious file (e.g., a web shell, executable, or script) to the vulnerable endpoint. The server then stores the file in a location accessible via the web server, allowing the attacker to execute arbitrary code or access sensitive data.

The exact endpoint and upload mechanism are not publicly documented, but typical ArcGIS Server upload endpoints include /upload, /fileUpload, or similar paths. The vulnerability is classified under CWE-434 (Unrestricted Upload of File with Dangerous Type).

Vulnerable vs. Patched Code

No patched version is available. The vulnerable code likely lacks file type validation and path sanitization. A secure implementation would:

• Validate file extension and MIME type against a whitelist.
• Store uploaded files outside the web root.
• Rename files to prevent path traversal.
• Require authentication for upload operations.

Example of vulnerable pseudo-code:

def handle_upload(request):
    file = request.files['file']
    filename = file.filename
    file.save('/var/www/uploads/' + filename)
    return "Upload successful"

Example of patched pseudo-code:

import os
import uuid

ALLOWED_EXTENSIONS = {'png', 'jpg', 'gif'}

def handle_upload(request):
    if not request.authenticated:
        return "Unauthorized", 401
    file = request.files['file']
    ext = file.filename.rsplit('.', 1)[1].lower()
    if ext not in ALLOWED_EXTENSIONS:
        return "Invalid file type", 400
    safe_name = str(uuid.uuid4()) + '.' + ext
    file.save('/var/www/secure_uploads/' + safe_name)
    return "Upload successful"

Exploitation & Lab Setup

Red Team

Since no public exploit code is available, a red team would need to:

1. Identify the vulnerable upload endpoint (e.g., via directory brute-forcing or API documentation).
2. Craft a malicious file (e.g., a JSP web shell for Tomcat-based ArcGIS Server).
3. Send a POST request with the file to the endpoint.
4. Access the uploaded file via the web server to execute commands.

Example curl command:

curl -X POST -F "file=@shell.jsp" http://target.com/arcgis/upload

Expected output: The server returns a success message and the path to the uploaded file.

Blue Team

Blue team detection should focus on:

• Monitoring for unusual file uploads to ArcGIS Server endpoints.
• Inspecting uploaded files for malicious content (e.g., web shells, executables).
• Implementing network segmentation to limit exposure of ArcGIS Server.
• Deploying WAF rules to block uploads of executable file types.

Detection steps:

1. Enable logging on ArcGIS Server upload endpoints.
2. Monitor logs for POST requests to /upload or similar paths.
3. Alert on file extensions such as .jsp, .asp, .php, .exe, .sh.
4. Use file integrity monitoring to detect new files in web-accessible directories.

Indicators of Compromise (IOCs)

• File paths: /var/www/uploads/*, /opt/arcgis/server/upload/*
• File names: shell.jsp, cmd.aspx, backdoor.php
• Network patterns: POST requests to /arcgis/upload or /upload with multipart/form-data
• Log entries: POST /arcgis/upload HTTP/1.1 with status 200
• Processes: java or tomcat spawning child processes (e.g., cmd.exe, /bin/sh)

Detection Engineering

YARA Rule

rule CVE_2026_9182_ArcGIS_Upload {
    meta:
        description = "Detects malicious files uploaded via CVE-2026-9182"
        author = "Valters IT"
        date = "2026-01-01"
        reference = "CVE-2026-9182"
    strings:
        $jsp_webshell = "<%="
        $php_webshell = "<?php"
        $asp_webshell = "<%"
        $exe_magic = {4D 5A}  // MZ header
        $elf_magic = {7F 45 4C 46}  // ELF header
    condition:
        any of ($jsp_webshell, $php_webshell, $asp_webshell, $exe_magic, $elf_magic)
}

Sigma Rule

title: ArcGIS Server Unrestricted File Upload
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects POST requests to ArcGIS Server upload endpoints
author: Valters IT
date: 2026-01-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem:
            - '/arcgis/upload'
            - '/upload'
    condition: selection
falsepositives:
    - Legitimate file uploads by authorized users
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2026-9182 ArcGIS Server Unrestricted File Upload"; flow:to_server; content:"POST"; http_method; content:"/arcgis/upload"; http_uri; content:"multipart/form-data"; http_header; sid:1000001; rev:1;)

Remediation & Mitigation

Since no official patch is available, the following mitigations are recommended:

1. Disable the vulnerable endpoint if not required.
2. Implement authentication for all upload operations.
3. Use a Web Application Firewall (WAF) to block uploads of executable file types.
4. Restrict file storage to a non-web-accessible directory.
5. Monitor logs for suspicious upload activity.
6. Apply virtual patching via IDS/IPS rules (e.g., the Suricata rule above).
7. Segment the network to limit exposure of ArcGIS Server.

Valters IT
DevSecOps & Cyber Threat Intelligence