CVE-2025-67539 is a DOM-based Cross-site Scripting (XSS) vulnerability affecting Select-Themes Select Core, a WordPress theme framework used to build websites. The vulnerability exists due to improper neutralization of user-supplied input during the generation of web pages, allowing malicious scripts to be injected and executed in the victim's browser environment. This type of XSS is client-side and occurs when the web application uses unsafe JavaScript methods to process input that is then reflected in the DOM without proper sanitization or encoding. The affected versions include all releases prior to 2.6, with no specific version range provided. The vulnerability requires low privileges (PR:L) and user interaction (UI:R), meaning an attacker must trick a user into clicking a crafted link or visiting a malicious page. The CVSS 3.1 base score is 6.5, reflecting a medium severity with network attack vector (AV:N), low attack complexity (AC:L), partial impact on confidentiality, integrity, and availability (C:L/I:L/A:L), and scope change (S:C), indicating that the vulnerability can affect resources beyond the initially vulnerable component. No known exploits have been reported in the wild yet, but the vulnerability could be leveraged to steal session cookies, perform actions on behalf of the user, or redirect users to malicious sites. The vulnerability is particularly relevant for websites using Select Core themes, which are common in WordPress-based environments, often used by small to medium enterprises and content-driven websites. The lack of available patches at the time of publication necessitates immediate attention to mitigation strategies.

For European organizations, this vulnerability can lead to client-side attacks that compromise user sessions, steal sensitive information, or facilitate phishing and social engineering campaigns. The partial compromise of confidentiality, integrity, and availability can impact customer trust, lead to data breaches, and cause reputational damage. Organizations relying on Select Core themes for their web presence, especially e-commerce, government portals, and media sites, face risks of unauthorized actions performed in the context of authenticated users. The vulnerability's exploitation could also serve as an entry point for more complex attacks, such as privilege escalation or lateral movement within internal networks if combined with other vulnerabilities. Given the widespread use of WordPress and its themes in Europe, the potential impact is significant, particularly for sectors with high web traffic and sensitive user data. Additionally, regulatory frameworks like GDPR impose strict requirements on data protection, making exploitation consequences more severe in terms of compliance and fines.

1. Monitor Select-Themes official channels for patches addressing CVE-2025-67539 and apply them promptly once released. 2. Implement strict input validation and output encoding on all user-supplied data, especially in JavaScript contexts, to prevent injection of malicious scripts. 3. Deploy Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of XSS attacks. 4. Conduct regular security audits and penetration testing focusing on client-side vulnerabilities in web applications using Select Core themes. 5. Educate users and administrators about phishing risks and safe browsing practices to reduce the likelihood of successful exploitation requiring user interaction. 6. Utilize web application firewalls (WAFs) with rules tailored to detect and block XSS payloads targeting Select Core themes. 7. Consider isolating critical web application components and minimizing the use of third-party themes or plugins with known vulnerabilities. 8. Review and harden session management mechanisms to limit the damage in case of session hijacking attempts.