---
title: "Festo LX Appliance XSS Vulnerability: Remote Exploitation Risk"
short_title: "Festo LX Appliance XSS flaw exposes systems"
description: "Festo LX Appliance versions before June 2023 face a critical XSS vulnerability (CVE-2021-23414). Learn how to mitigate risks and secure your systems now."
author: "Vitus"
date: 2025-01-24
categories: [Cybersecurity, Vulnerabilities]
tags: [xss, festo, cve-2021-23414, industrial-security, cybersecurity]
score: 0.65
cve_ids: [CVE-2021-23414]
---
TL;DR
Festo’s LX Appliance, used in critical infrastructure sectors, is vulnerable to a Cross-Site Scripting (XSS) attack (CVE-2021-23414) in versions prior to June 2023. Exploitable remotely with low complexity, this flaw allows high-privilege users to execute arbitrary code. Festo has released mitigations, including updates and defensive strategies to reduce exposure.
---
Main Content
Critical XSS Vulnerability in Festo LX Appliance Puts Industrial Systems at Risk
A Cross-Site Scripting (XSS) vulnerability in Festo’s LX Appliance has raised alarms across critical infrastructure sectors, including energy, manufacturing, and communications. Tracked as CVE-2021-23414, this flaw affects versions of the LX Appliance released before June 2023 and could enable attackers to execute malicious code remotely. With a CVSS v3.1 score of 6.1, the vulnerability underscores the urgent need for organizations to apply patches and adopt defensive measures.
---
Key Points
- Vulnerability Type: Cross-Site Scripting (XSS) in the `src` attribute of the `track` tag.
- Affected Products: Festo LX Appliance versions prior to June 2023.
- Exploitation Risk: Remotely exploitable with low attack complexity; requires a high-privilege account.
- Impact: Arbitrary code execution, potential data theft, or unauthorized system access.
- Mitigation: Update to the latest version via Festo’s services department or apply recommended defensive strategies.
---
Technical Details
#### Affected Systems
Festo has confirmed that the following product is vulnerable:
- Festo Software LX Appliance: All versions released before June 2023.
Vulnerability Overview
The vulnerability stems from improper neutralization of input during web page generation, specifically in the `src` attribute of the `track` tag. This flaw allows attackers to bypass HTML escaping mechanisms and inject malicious scripts. The issue is rooted in the video.js package (versions before 7.14.3), which is used by the LX Appliance.
#### CVE Details
- CVE ID: [CVE-2021-23414](https://www.cve.org/CVERecord?id=CVE-2021-23414)
- CVSS v3.1 Score: 6.1 (Medium Severity)
- Vector String: `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`
- Attack Vector (AV): Network (remotely exploitable)
- Attack Complexity (AC): Low
- Privileges Required (PR): None (but requires a high-privilege user context)
- User Interaction (UI): Required (victim must interact with malicious content)
- Scope (S): Changed (impacts beyond the vulnerable component)
- Confidentiality (C): Low
- Integrity (I): Low
- Availability (A): None
---
Impact Assessment
#### Sectors at Risk
The Festo LX Appliance is deployed across multiple critical infrastructure sectors, including:
- Commercial Facilities
- Communications
- Critical Manufacturing
- Energy
Given its global deployment, the vulnerability poses a significant risk to organizations worldwide, particularly those relying on industrial control systems (ICS).
#### Potential Consequences
Successful exploitation of this XSS vulnerability could allow attackers to:
- Execute arbitrary JavaScript code in the context of a victim’s browser.
- Steal sensitive session cookies or credentials.
- Redirect users to malicious websites.
- Perform actions on behalf of high-privilege users, leading to unauthorized system changes or data breaches.
While no public exploitation has been reported to CISA as of this writing, the low attack complexity and remote exploitability make this a high-priority concern for affected organizations.
---
Mitigation Steps
Festo has outlined specific workarounds and mitigations to reduce the risk of exploitation:
#### Immediate Actions
1. Update the LX Appliance:
- Contact Festo’s Didactic services department at services.didactic@festo.com to upgrade to the latest version.
- Refer to Festo’s security advisory [FSA-202301](https://certvde.com/en/advisories/VDE-2023-040/) for detailed guidance.
2. Network-Level Protections:
- Minimize network exposure for control system devices. Ensure they are not accessible from the Internet.
- Isolate control system networks behind firewalls and segregate them from business networks.
- Use secure remote access methods, such as Virtual Private Networks (VPNs), and ensure they are updated to the latest version.
3. Defensive Strategies:
- Follow CISA’s recommended practices for [ICS security](https://www.cisa.gov/resources-tools/resources/ics-recommended-practices).
- Implement Defense-in-Depth strategies to enhance cybersecurity resilience. Refer to CISA’s guide: [Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies](https://us-cert.cisa.gov/sites/default/files/recommended_practices/NCCIC_ICS-CERT_Defense_in_Depth_2016_S508C.pdf).
- Monitor for suspicious activity and report incidents to CISA for correlation and tracking.
4. User Awareness:
- Train employees to recognize and avoid phishing and social engineering attacks.
- Avoid clicking on unsolicited links or attachments in emails.
- Refer to CISA’s resources on [Recognizing and Avoiding Email Scams](https://www.cisa.gov/uscert/sites/default/files/publications/emailscams0905.pdf) and [Avoiding Social Engineering Attacks](https://www.cisa.gov/uscert/ncas/tips/ST04-014).
---
Conclusion
The XSS vulnerability in Festo’s LX Appliance (CVE-2021-23414) serves as a critical reminder of the risks posed by improper input validation in industrial software. While the flaw requires a high-privilege user context for exploitation, its remote accessibility and low attack complexity demand immediate action from affected organizations.
By updating to the latest version, implementing network-level protections, and adopting proactive cybersecurity strategies, organizations can mitigate risks and safeguard their critical infrastructure. Stay vigilant, monitor for updates, and prioritize security to prevent potential breaches.
---
References
[^1]: CISA. "[ICSA-25-343-02: Festo LX Appliance Cross-Site Scripting Vulnerability](https://www.cisa.gov/news-events/ics-advisories/icsa-25-343-02)". Retrieved 2025-01-24.
[^2]: Festo. "[FSA-202301: Cross-Site-Scripting (XSS) Vulnerability in LX Appliance](https://certvde.com/en/advisories/VDE-2023-040/)". Retrieved 2025-01-24.
[^3]: MITRE. "[CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')](https://cwe.mitre.org/data/definitions/79.html)". Retrieved 2025-01-24.
[^4]: CVE. "[CVE-2021-23414 Detail](https://www.cve.org/CVERecord?id=CVE-2021-23414)". Retrieved 2025-01-24.