CVE-2026-63356 in Siemens
Summary
by MITRE • 10/13/2026
Affected devices do not properly sanitize calculated signal names contained in imported CSV trace files before including them in error messages 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. Attacker-controlled JavaScript could be executed in the user’s browser session when the resulting error message is displayed.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability described constitutes a Stored Cross-Site Scripting (XSS) flaw within the web interface of affected network diagnostic devices, specifically impacting the Trace page functionality that processes imported CSV trace files. The core technical deficiency lies in the application's failure to properly sanitize calculated signal names extracted from these uploaded files before they are rendered back into the user interface context via error messages. When a device receives an import request containing maliciously crafted data within the signal name fields, the backend processing logic incorporates this unsanitized input directly into HTML content without applying adequate encoding or filtering mechanisms. This oversight allows attackers to inject executable JavaScript payloads that persist in the system's state until triggered by legitimate administrative actions.
The operational impact of this vulnerability is significant due to its reliance on social engineering tactics combined with specific privilege requirements. An attacker must first convince an authorized user possessing the Read diagnostics function right to import a specially crafted CSV trace file into the device interface. This requirement limits the attack surface to authenticated users but does not mitigate the risk for internal threats or compromised accounts. Once the malicious file is imported, the system generates an error message that includes the unsanitized signal name containing the injected script. When this error dialog is displayed in the user's browser session, the JavaScript code executes with the same privileges and context as the rest of the web application. This execution environment allows for potential cookie theft, session hijacking, credential harvesting, or further lateral movement within the network if the compromised administrative account has broader access rights beyond diagnostics.
From a classification perspective, this vulnerability aligns closely with CWE-79, which defines Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The specific vector involves stored input where user-controllable data is saved by the web application and later retrieved without proper validation, leading to execution in another user's browser. In terms of offensive security frameworks such as MITRE ATT&CK, this behavior maps to techniques involving Client-side Injection (T1059) and potentially Data from Information Repositories if the attacker leverages the compromised session to exfiltrate sensitive diagnostic data or configuration details stored on the device. The attack chain typically follows a pattern of Initial Access through social engineering followed by Execution via browser-based script injection, facilitating potential Privilege Escalation depending on the scope of the victim's permissions.
Mitigation strategies should focus primarily on implementing robust input validation and output encoding practices within the application logic responsible for processing CSV imports. Developers must ensure that all data derived from uploaded files is treated as untrusted and undergo strict sanitization before being included in any HTML context, particularly within dynamic error messages or UI components. Implementing a Content Security Policy (CSP) can also serve as an effective defense-in-depth measure by restricting the sources from which scripts are allowed to execute, thereby neutralizing the impact of injected payloads even if they bypass input filters. Additionally, applying principle of least privilege ensures that users with Read diagnostics rights do not possess unnecessary administrative capabilities that could be exploited following a successful XSS attack. Regular security code reviews and automated static analysis tools configured to detect missing output encoding are essential for preventing similar vulnerabilities in future software updates or related modules within the device's firmware ecosystem.