CVE-2026-82763 in FX3000 Series
Summary
by MITRE • 09/14/2026
Cross-site scripting vulnerability exists in Contec FX5000 series, FX4000 series, and FX3000 series. If this vulnerability is exploited, an arbitrary script may be executed on a logged-in user's web browser.
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Analysis
by VulDB Data Team • 09/14/2026
The identified cross-site scripting (XSS) vulnerability affects the Contec FX5000, FX4000, and FX3000 series of industrial devices, representing a significant security risk for environments relying on these systems for operational monitoring or control. This flaw stems from insufficient validation or sanitization of user-supplied input within the web-based management interface of the affected hardware. When an attacker crafts malicious content containing executable JavaScript code and tricks a legitimate, authenticated administrator into viewing this content through their browser, the vulnerable application fails to neutralize the script before rendering it in the HTML output. This failure allows the arbitrary script to execute within the security context of the logged-in user's session, effectively bypassing same-origin policy restrictions that are designed to prevent malicious scripts from accessing data on other websites or applications.
From a technical perspective, this vulnerability aligns with CWE-79, which classifies improper neutralization of input during web page generation as a critical weakness in web application security. The exploitation mechanism typically involves the injection of script tags, event handlers, or encoded payloads into fields that are reflected back to the user without proper encoding or filtering. Because the victim is already authenticated, the executed scripts inherit the privileges associated with that session. This capability transforms what might otherwise be a nuisance-level issue into a severe compromise of confidentiality and integrity. The attacker can manipulate page content, steal sensitive configuration data, capture administrative credentials via keyloggers embedded in the malicious script, or perform actions on behalf of the user without their knowledge or consent.
The operational impact extends beyond simple defacement or session hijacking within the local context. In industrial control systems where these Contec devices are often deployed as gateways or controllers, an XSS vulnerability can serve as a pivot point for more sophisticated attacks. An attacker could potentially use the compromised browser to interact with internal network services that are not directly exposed to the internet but are accessible from the management VLAN. This creates a pathway for lateral movement within the industrial network infrastructure. Furthermore, if the device manages critical processes or interfaces with other SCADA components, manipulating the interface through XSS could lead to incorrect operational decisions or disruption of monitoring capabilities, thereby impacting business continuity and physical safety depending on the specific application domain.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The primary technical fix involves implementing strict input validation and output encoding for all user-controllable data rendered in web pages. Developers should employ context-aware encoding to ensure that special characters are converted into their safe HTML entities before being displayed, thereby preventing the browser from interpreting them as executable code. Additionally, deploying Content Security Policy (CSP) headers can significantly reduce the impact of XSS attacks by restricting the sources from which scripts can be loaded and executed. For administrators currently using these devices, it is crucial to ensure that firmware versions are updated to include patches released by Contec addressing this specific flaw. Access controls should also be reviewed to limit administrative access to trusted IP addresses only, reducing the attack surface available for social engineering or direct exploitation attempts. Regular security audits of web interfaces and adherence to OWASP Top 10 guidelines will further strengthen resilience against such vulnerabilities.