CVE-2026-73169 in EKI-1242EIMS
Summary
by MITRE • 09/16/2026
Nozomi Networks Labs identified a CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Modbus transaction management interface of Advantech EKI-1242EIMS in firmware version V1.06.01 that allows a remote authenticated attacker to store malicious script content that executes in the browser of any administrator who later opens an affected management page.
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Analysis
by VulDB Data Team • 09/16/2026
The vulnerability identified by Nozomi Networks Labs represents a significant security risk within industrial control systems, specifically targeting the Advantech EKI-1242EIMS managed Ethernet switch running firmware version V1.06.01. This flaw is classified under CWE-79, which denotes Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting or XSS. The specific manifestation of this vulnerability occurs within the Modbus transaction management interface, a critical component for monitoring and controlling industrial communication protocols over Ethernet networks. Unlike reflected XSS attacks that require immediate user interaction with malicious links, this is a stored persistent cross-site scripting vulnerability. This means that once an attacker successfully injects malicious script content into the system's database or configuration storage via the Modbus transaction management interface, the payload remains on the server until manually removed.
The operational impact of this vulnerability is severe due to its ability to execute in the browser context of any administrator who subsequently accesses the affected management page. Because the attacker must be authenticated, they typically possess elevated privileges within the device's administrative console. However, even with authentication, the injection of arbitrary JavaScript code allows for session hijacking, credential theft, or defacement of the management interface. An adversary can exploit this to steal sensitive configuration data, manipulate network traffic settings, or use the compromised switch as a pivot point for further attacks against other devices on the industrial control system network. The persistence of the script ensures that every administrative login becomes a potential attack vector until the malicious content is purged from the system storage.
From an offensive security perspective, this vulnerability aligns with MITRE ATT&CK techniques related to Collection via Browser Capture and Command and Scripting Interpreter within local environments. An attacker leveraging this flaw can bypass traditional network perimeter defenses by operating entirely within the authenticated administrative session of a trusted industrial device. The ability to execute scripts in the context of an administrator significantly lowers the barrier for subsequent exploitation, as it facilitates the extraction of cookies, HTTP headers, and potentially other sensitive information stored locally in the browser cache or local storage associated with the management interface.
Mitigation strategies must focus on both immediate remediation and long-term secure development practices. The primary mitigation is to apply the firmware update provided by Advantech that addresses this specific input validation flaw. Until an official patch is available, administrators should restrict access to the Modbus transaction management interface using strict network segmentation policies, ensuring it is only accessible from trusted administrative workstations on isolated VLANs. Input sanitization and output encoding must be rigorously implemented in all web interfaces handling user-supplied data, particularly those interacting with industrial protocols like Modbus. Additionally, implementing a Content Security Policy (CSP) can help mitigate the impact of any successful XSS injection by restricting the sources from which scripts are allowed to execute, thereby preventing unauthorized code execution even if malicious input is stored on the server.