CVE-2026-102459: EasyFlow .NET Reflected XSS Vulnerability

CVE-2026-102459 Overview

CVE-2026-102459 is a Reflected Cross-Site Scripting (XSS) vulnerability in Digiwin EasyFlow .NET. Unauthenticated remote attackers can execute arbitrary JavaScript in a victim's browser by delivering a crafted link through phishing. The flaw is classified under CWE-79, Improper Neutralization of Input During Web Page Generation. Exploitation requires user interaction, typically clicking a malicious URL, but no authentication is needed. Successful attacks can compromise session confidentiality and integrity within the affected web application context.

Critical Impact
Attackers can hijack authenticated user sessions, exfiltrate application data, or redirect victims to attacker-controlled content by luring users to a crafted EasyFlow .NET URL.

Affected Products

Digiwin EasyFlow .NET

Discovery Timeline

2026-09-30 - CVE-2026-102459 published to NVD
2026-09-30 - Last updated in NVD database

Technical Details for CVE-2026-102459

Vulnerability Analysis

EasyFlow .NET fails to properly neutralize attacker-controlled input before reflecting it into HTTP responses. When a victim follows a crafted URL, the injected payload renders inline in the browser and executes with the origin's privileges. Because the flaw is reflected rather than stored, exploitation depends on social engineering to place the malicious link in front of an authenticated user.

The scope covers script execution in the victim's session context. Attackers can read Document Object Model (DOM) content, issue authenticated requests on behalf of the user, capture form input, and pivot into internal workflows exposed by EasyFlow. The vulnerability does not require prior authentication on the attacker's side, which broadens the pool of possible exploit distribution channels.

Root Cause

The root cause is missing or insufficient output encoding on user-supplied parameters that are reflected into server responses. The application returns request data into HTML or JavaScript contexts without contextual escaping, allowing <script> tags or event handlers to execute.

Attack Vector

An attacker crafts a URL containing a JavaScript payload in a vulnerable request parameter and delivers it through phishing email, chat, or a compromised third-party site. When the target clicks the link, the EasyFlow .NET server reflects the payload into the response and the browser executes it under the application's origin.

No verified public proof-of-concept exploit code is available. See the TW-CERT Security Advisory for vendor-coordinated details.

Detection Methods for CVE-2026-102459

Indicators of Compromise

Inbound HTTP requests to EasyFlow .NET endpoints containing <script>, javascript:, onerror=, onload=, or URL-encoded equivalents such as %3Cscript%3E in query strings.
Referrer headers on EasyFlow requests originating from unexpected external domains, mail gateways, or URL shorteners.
Anomalous outbound requests from user browsers to unfamiliar domains immediately after loading an EasyFlow page.

Detection Strategies

Deploy web application firewall (WAF) rules that flag reflected input containing HTML tags or JavaScript event handlers in EasyFlow request parameters.
Correlate web server access logs with email gateway telemetry to identify phishing campaigns delivering crafted EasyFlow URLs.
Enable Content Security Policy (CSP) violation reporting to surface unexpected inline script execution on EasyFlow pages.

Monitoring Recommendations

Alert on repeated requests to the same EasyFlow endpoint with varying script-like payloads, which indicates payload tuning.
Monitor session cookie access patterns and geographic anomalies for accounts that interacted with suspicious EasyFlow URLs.
Track user-reported phishing submissions that reference EasyFlow application URLs for triage.

How to Mitigate CVE-2026-102459

Immediate Actions Required

Apply the vendor fix from Digiwin as referenced in the TW-CERT Security Advisory.
Notify EasyFlow users about the phishing risk and reinforce URL inspection practices before clicking application links.
Rotate session cookies and force re-authentication for users suspected of interacting with malicious links.

Patch Information

Digiwin has coordinated remediation through Taiwan's TW-CERT. Refer to the TW-CERT Security Advisory and the TW-CERT Incident Report for fixed version numbers and upgrade guidance specific to your EasyFlow .NET deployment.

Workarounds

Enforce a strict Content Security Policy that disallows inline scripts and restricts script sources to trusted origins.
Configure the reverse proxy or WAF to reject requests containing script tags, event handlers, or JavaScript URI schemes in query parameters.
Set the HttpOnly and Secure flags on session cookies to reduce the impact of successful script execution.

bash

# Example WAF rule concept (ModSecurity) to block reflected XSS payloads
SecRule ARGS "@rx (?i)(<script|javascript:|onerror\s*=|onload\s*=)" \
    "id:1026102459,phase:2,deny,status:403,msg:'EasyFlow XSS attempt blocked'"