CVE-2026-102454: EasyFlow .NET Arbitrary File Upload RCE

CVE-2026-102454 Overview

CVE-2026-102454 is an arbitrary file upload vulnerability in Digiwin EasyFlow .NET. Authenticated remote attackers with high privileges can upload web shell backdoors to the server. Successful exploitation allows arbitrary code execution in the context of the web application. The weakness is classified as [CWE-434] Unrestricted Upload of File with Dangerous Type. The vulnerability was disclosed through Taiwan's Computer Emergency Response Team (TWCERT).

Critical Impact

Privileged attackers can upload executable web shells and achieve arbitrary code execution on servers running Digiwin EasyFlow .NET.

Affected Products

• Digiwin EasyFlow .NET

Discovery Timeline

• 2026-09-30 - CVE-2026-102454 published to the National Vulnerability Database
• 2026-09-30 - Record last modified in NVD
• Advisories - TWCERT security advisories 11240 and 11241 published

Technical Details for CVE-2026-102454

Vulnerability Analysis

EasyFlow .NET exposes a file upload endpoint that does not adequately validate the type, extension, or content of uploaded files. An authenticated attacker with elevated privileges can submit a request containing a server-executable file, such as an .aspx or .ashx web shell. The application writes the file into a location served by the web server, allowing subsequent HTTP requests to execute the attacker-controlled code. Once executed, the web shell runs with the identity of the web application process and can be used to run system commands, pivot inside the network, and stage further payloads.

Root Cause

The root cause is unrestricted file upload handling [CWE-434]. The application relies on client-supplied metadata rather than enforcing a strict allow-list of MIME types, extensions, and file signatures. It also stores uploaded files in a directory where the .NET runtime processes server-side scripts.

Attack Vector

Exploitation requires network access to the EasyFlow .NET web interface and valid high-privilege credentials. The attacker authenticates, submits a crafted upload request containing a web shell, and then issues a follow-up HTTP request to the shell's URL to trigger code execution. Refer to the TWCERT Security Advisory 11241 and TWCERT Security Advisory 11240 for vendor-coordinated details.

Detection Methods for CVE-2026-102454

Indicators of Compromise

• Unexpected .aspx, .ashx, .asmx, or .config files inside EasyFlow .NET upload or attachment directories.
• Web server access logs showing POST requests to upload endpoints followed by GET requests to newly created files in those paths.
• IIS worker process (w3wp.exe) spawning cmd.exe, powershell.exe, or other shells.
• Outbound network connections from the EasyFlow .NET application server to unfamiliar hosts following upload activity.

Detection Strategies

• Alert on file writes with executable extensions inside web-accessible EasyFlow directories.
• Correlate authenticated upload requests with subsequent execution of new files within a short time window.
• Monitor for anomalous child processes of the web application worker process.

Monitoring Recommendations

• Forward IIS and application logs to a centralized SIEM for retention and correlation.
• Baseline expected file types and paths under the EasyFlow web root and alert on deviations.
• Track authentication events for high-privilege accounts and flag uploads occurring outside of change windows.

How to Mitigate CVE-2026-102454

Immediate Actions Required

• Apply the vendor-supplied fix referenced in the TWCERT advisories as soon as it is available for your EasyFlow .NET version.
• Rotate credentials for all high-privilege EasyFlow accounts and audit recent administrative activity.
• Inspect upload directories for unauthorized files and remove any confirmed web shells.
• Restrict network access to the EasyFlow .NET management interface to trusted administrative networks.

Patch Information

Consult Digiwin and the TWCERT Security Advisory 11241 for the current patched build of EasyFlow .NET. Confirm the fixed version with the vendor before deployment and validate installation in a staging environment prior to production rollout.

Workarounds

• Enforce least privilege by removing unnecessary high-privilege accounts that can access upload functionality.
• Configure IIS to deny script execution in directories that store user-uploaded content using <handlers> removal rules.
• Deploy a web application firewall rule that blocks uploads containing executable extensions or server-side script signatures.
• Require multi-factor authentication for administrative access to EasyFlow .NET.

# Example IIS web.config snippet to disable script execution in an uploads directory
# Place inside the upload folder's web.config
<configuration>
  <system.webServer>
    <handlers accessPolicy="Read" />
    <staticContent>
      <clientCache cacheControlMode="DisableCache" />
    </staticContent>
  </system.webServer>
</configuration>