CVE-2026-63351 in Siemens
Summary
by MITRE • 10/13/2026
Affected devices do not properly validate and sanitize visual properties of calculated signals contained in imported CSV trace files before rendering them on the Trace page.
This could allow an attacker to social engineer an authorized user who holds the function right “Read diagnostics” into importing a specially crafted trace file. Successful exploitation could allow attacker-controlled JavaScript to execute in the user’s browser session and perform PLC operations through the web server within the scope of the user’s authorization.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability described constitutes a critical security flaw rooted in insufficient input validation and sanitization mechanisms within the device's web interface, specifically concerning the processing of imported CSV trace files. When users upload these files for analysis on the Trace page, the application fails to adequately sanitize visual properties associated with calculated signals before rendering them. This lack of rigorous data handling allows malicious actors to embed executable content, such as JavaScript code, directly within the structured data fields of the CSV file. The core technical failure lies in the absence of strict type checking and output encoding for dynamic content derived from user-supplied inputs, which violates fundamental principles of secure coding practices regarding untrusted data processing.
This flaw enables a classic Stored Cross-Site Scripting scenario where the malicious payload is persisted within the application's context through the uploaded file rather than being injected via URL parameters or form fields in real-time. An attacker can craft a specially designed CSV trace file containing obfuscated JavaScript that triggers upon rendering by the browser. The exploitation strategy relies heavily on social engineering, requiring the attacker to deceive an authorized user with Read diagnostics privileges into importing this malicious artifact. Once imported and rendered, the embedded script executes within the security context of the victim's active session, granting the attacker the ability to interact with the web server as if they were the legitimate user.
The operational impact is severe due to the high level of access granted by the compromised account. Since the execution occurs within the scope of the user’s authorization, which includes Read diagnostics permissions, the attacker gains the capability to perform PLC operations through the web server. This means that industrial control systems or programmable logic controllers connected to the device can be manipulated remotely via the browser interface. Such manipulation could lead to unauthorized changes in process parameters, disruption of automated workflows, or even physical damage to machinery if critical thresholds are exceeded. The ability to execute arbitrary commands effectively bypasses network-level security controls and authentication mechanisms by leveraging trusted user sessions.
From a classification perspective, this vulnerability aligns with CWE-79 Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. Furthermore, the exploitation technique maps directly to MITRE ATT&CK techniques involving Client-side Injection and potentially Command and Control via application layer protocols if further lateral movement is attempted. The attack vector leverages user interaction, categorizing it under social engineering tactics that exploit human trust in system functionality rather than exploiting a direct software bug in network services.
Mitigation strategies must focus on implementing robust input validation and output encoding mechanisms at multiple layers of the architecture. Developers should enforce strict schema validation for all imported CSV files, ensuring that only expected data types are processed and rejecting any content containing script tags or event handlers. Additionally, Content Security Policy headers should be configured to restrict inline JavaScript execution, thereby neutralizing the impact even if malicious code is inadvertently rendered. Implementing server-side sanitization libraries that automatically escape special characters before rendering them in HTML contexts is essential. Regular security audits focusing on web application logic and penetration testing of file upload functionalities will help identify similar weaknesses before they can be exploited by adversaries targeting industrial control environments.