CVE-2025-34257 is a stored cross-site scripting (XSS) vulnerability identified in Advantech Co., Ltd.'s WISE-DeviceOn Server, specifically affecting versions prior to 5.4. The vulnerability resides in the /rmm/v1/action/defined endpoint, where the defined_name parameter is accepted from authenticated users when creating tasks. This parameter's value is stored without proper HTML sanitization and later rendered on the Overview page. Because the input is not neutralized, an attacker with authenticated access can inject malicious JavaScript code into defined_name. When other users view the Overview page containing the malicious task, the script executes in their browser context, potentially allowing session hijacking, theft of cookies, or execution of unauthorized actions on behalf of the victim. The vulnerability requires the attacker to have at least authenticated privileges to create tasks, and victims must interact by viewing the affected page. The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required beyond authentication, user interaction required, and low impact on confidentiality and integrity but limited availability impact. No public exploits are known at this time, but the stored nature of the XSS increases the risk of persistent attacks within affected environments. The lack of available patches at the time of reporting necessitates immediate mitigation steps.

For European organizations, the impact of this vulnerability can be significant, especially for those relying on Advantech WISE-DeviceOn Server for industrial IoT device management and monitoring. Successful exploitation could lead to session hijacking, unauthorized command execution, and potential lateral movement within the network. This could compromise operational technology (OT) environments, leading to disruption of critical infrastructure or manufacturing processes. The stored XSS nature means multiple users could be affected once the malicious script is injected. Confidentiality of session tokens and integrity of user actions are at risk, potentially enabling attackers to escalate privileges or manipulate device management tasks. Given the increasing integration of IT and OT in European industries, such vulnerabilities pose a risk to both cybersecurity and physical safety. The medium CVSS score reflects moderate risk but should not be underestimated in critical sectors such as energy, manufacturing, and transportation.

1. Upgrade to Advantech WISE-DeviceOn Server version 5.4 or later once available, as this will include the official patch addressing the vulnerability. 2. Until patching is possible, restrict task creation privileges to only highly trusted users to minimize the risk of malicious input. 3. Implement web application firewall (WAF) rules to detect and block suspicious script payloads targeting the /rmm/v1/action/defined endpoint. 4. Conduct regular monitoring and auditing of tasks created in the system to identify any anomalous or suspicious defined_name values. 5. Educate users to avoid clicking on suspicious links or viewing untrusted tasks within the Overview page. 6. Employ Content Security Policy (CSP) headers to limit the execution of inline scripts and reduce the impact of XSS attacks. 7. Review and enhance input validation and output encoding practices in custom integrations or extensions interacting with the WISE-DeviceOn Server. 8. Isolate the management interface from general user networks to reduce exposure. 9. Maintain up-to-date backups and incident response plans tailored for OT environments.