CVE-2025-62135 is a DOM-based Cross-site Scripting (XSS) vulnerability classified under CWE-79, found in the landwire Responsive Block Control product up to version 1.2.9. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, which allows malicious scripts to be injected and executed in the victim’s browser context. This type of XSS is client-side and occurs when the web application uses unsafe JavaScript methods to process input data without adequate sanitization or encoding. The vulnerability’s CVSS v3.1 score is 6.5, indicating a medium severity level. The attack vector is network-based (AV:N), with low attack complexity (AC:L), but requires privileges (PR:L) and user interaction (UI:R). The scope is changed (S:C), meaning the vulnerability can affect components beyond the initially vulnerable one. The impact affects confidentiality, integrity, and availability to a limited extent (C:L/I:L/A:L). Although no known exploits are currently reported in the wild and no patches have been released, the vulnerability could be leveraged by attackers to perform session hijacking, steal sensitive information, or conduct unauthorized actions on behalf of users. The lack of patches necessitates immediate attention to mitigate risk. The vulnerability is particularly relevant for organizations that deploy landwire Responsive Block Control in their web environments, especially those serving sensitive or high-value data. The technical root cause is the failure to properly sanitize or encode input before it is reflected in the DOM, enabling attackers to craft payloads that execute arbitrary JavaScript code in users’ browsers.

For European organizations, this vulnerability poses a moderate risk to web applications utilizing the landwire Responsive Block Control, potentially exposing users to session hijacking, credential theft, or unauthorized actions. The compromise of user sessions or data could lead to reputational damage, regulatory penalties under GDPR, and operational disruptions. Since the vulnerability affects confidentiality, integrity, and availability to some degree, organizations handling sensitive personal data, financial transactions, or critical services are at higher risk. The requirement for some privileges and user interaction reduces the likelihood of mass exploitation but does not eliminate targeted attacks, especially against high-value targets. The absence of known exploits currently provides a window for proactive mitigation. However, if exploited, attackers could leverage this vulnerability to bypass security controls, escalate privileges, or pivot within the network. The impact is amplified in sectors such as finance, healthcare, government, and e-commerce, where trust and data protection are paramount.

European organizations should implement a multi-layered approach to mitigate this vulnerability: 1) Apply strict input validation and sanitization on all user-supplied data before processing or rendering it in the DOM. 2) Employ robust output encoding techniques, especially when inserting data into HTML, JavaScript, or URL contexts. 3) Implement Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of potential XSS payloads. 4) Conduct thorough code reviews and security testing focused on client-side script handling and DOM manipulation. 5) Monitor web application logs and user behavior for anomalies indicative of XSS exploitation attempts. 6) Engage with the vendor (landwire) for timely patch releases and apply updates as soon as they become available. 7) Educate developers and administrators on secure coding practices related to DOM-based XSS. 8) Consider deploying Web Application Firewalls (WAFs) with rules tailored to detect and block XSS attacks targeting this component. 9) Limit privileges required to access or modify vulnerable components to reduce attack surface. 10) Regularly update and audit third-party components integrated into web applications to identify and remediate vulnerabilities promptly.