CVE-2026-1011 identifies a stored cross-site scripting (XSS) vulnerability in the Altium Live platform, specifically within the Support Center's AddComment endpoint. The root cause is the absence of server-side input sanitization, allowing attackers to submit malicious HTML and JavaScript code through crafted POST requests. While the client interface attempts to mitigate XSS by applying HTML escaping, this is insufficient because the backend stores the raw input and renders it verbatim when support cases are accessed by other users, including support personnel with elevated privileges. This stored XSS flaw enables attackers to execute arbitrary JavaScript in the victim’s browser context, potentially leading to session hijacking, theft of sensitive information, or unauthorized actions performed with the victim’s privileges. The vulnerability is remotely exploitable without authentication but requires the victim to view the malicious comment to trigger the payload (user interaction). The CVSS v3.1 base score is 6.1, reflecting medium severity with network attack vector, low attack complexity, no privileges required, but user interaction needed. The scope is changed because the vulnerability affects other users beyond the attacker. No patches or known exploits are currently available, highlighting the need for proactive mitigation. The vulnerability is categorized under CWE-79 (Improper Neutralization of Input During Web Page Generation) and CWE-116 (Improper Encoding or Escaping of Output).

For European organizations using Altium Live, this vulnerability poses a risk of unauthorized script execution within the browsers of support staff and other users who access support cases. This can lead to compromised user sessions, theft of sensitive corporate or customer data, and potential unauthorized actions within the support platform. Given that support staff often have elevated privileges, exploitation could facilitate lateral movement or escalation within the organization’s support infrastructure. The impact on confidentiality and integrity is significant, though availability is not directly affected. Organizations in sectors relying heavily on Altium Live for electronics design support—such as manufacturing, engineering, and R&D—may face operational disruptions and reputational damage if exploited. The medium severity rating suggests a moderate but actionable risk, especially in environments where multiple users access support cases regularly.

1. Implement strict server-side input validation and sanitization for all inputs to the AddComment endpoint, ensuring that HTML and JavaScript content is either disallowed or properly escaped before storage. 2. Employ a Content Security Policy (CSP) to restrict the execution of unauthorized scripts in the browser context. 3. Conduct regular security code reviews and penetration testing focused on input handling in the support platform. 4. Educate support staff on the risks of clicking on suspicious comments or links within support cases. 5. Monitor logs for unusual POST requests to the AddComment endpoint that may indicate injection attempts. 6. If possible, isolate the support platform from critical internal networks to limit potential lateral movement. 7. Coordinate with Altium for official patches or updates addressing this vulnerability and apply them promptly once available. 8. Consider implementing web application firewalls (WAF) with rules to detect and block XSS payloads targeting the support center.