CVE-2025-62136 identifies a stored Cross-site Scripting (XSS) vulnerability in the ThinkUpThemes Melos WordPress theme, affecting versions up to 1.6.0. The root cause is improper neutralization of user-supplied input during web page generation, classified under CWE-79. This flaw allows attackers with at least low-level privileges (PR:L) to inject malicious scripts that are stored persistently within the application and executed in the context of other users' browsers when they view the affected pages. The vulnerability requires user interaction (UI:R), such as visiting a compromised page, and has a scope of changed security context (S:C), meaning it can affect resources beyond the initially compromised component. The CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L) reflects network attack vector, low attack complexity, low privileges required, and user interaction needed, with partial impacts on confidentiality, integrity, and availability. Although no public exploits are known at this time, the vulnerability poses a significant risk for web applications relying on Melos themes, potentially enabling session hijacking, credential theft, or site defacement. The lack of available patches at publication heightens the urgency for mitigation. The vulnerability was reserved in October 2025 and published at the end of December 2025, indicating recent discovery and disclosure. Organizations using this theme should prioritize remediation to prevent exploitation.

For European organizations, this vulnerability can lead to unauthorized script execution within users' browsers, compromising user sessions, stealing sensitive data such as authentication tokens, and potentially enabling further attacks like phishing or malware delivery. The impact extends to reputational damage and regulatory non-compliance, especially under GDPR, if personal data is exposed. E-commerce sites, government portals, and corporate websites using the Melos theme are particularly at risk. The medium severity rating reflects that while exploitation requires some privileges and user interaction, the consequences can affect confidentiality, integrity, and availability of web services. Disruption of service or defacement could also impact business continuity and customer trust. The absence of known exploits currently provides a window for proactive defense, but the risk of future exploitation remains significant.

Immediate mitigation steps include monitoring for updates or patches from ThinkUpThemes and applying them promptly once available. Until patches are released, organizations should implement strict input validation and output encoding on all user-supplied data to prevent script injection. Employing a robust Content Security Policy (CSP) can help restrict the execution of unauthorized scripts. Web application firewalls (WAFs) should be configured to detect and block XSS payloads targeting the Melos theme. Conducting thorough code reviews and penetration testing focused on input handling in the theme can identify additional weaknesses. Additionally, educating users about the risks of clicking suspicious links and maintaining up-to-date backups will aid in recovery if exploitation occurs. Disabling or limiting user-generated content features within the theme may reduce attack surface temporarily.