CVE-2025-62951 is a stored Cross-site Scripting (XSS) vulnerability identified in the icc0rz Interactive Content – H5P plugin, which is widely used to create and manage interactive web content, particularly in educational and e-learning environments. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, allowing malicious scripts to be stored and later executed in the browsers of other users who view the affected content. This stored XSS can be exploited by an attacker with at least limited privileges (PR:L) who can submit crafted input containing malicious JavaScript. When other users access the compromised content, the malicious script executes with their privileges, potentially leading to session hijacking, theft of sensitive information, defacement, or further exploitation of the victim’s browser environment. The CVSS 3.1 vector (AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L) indicates that the attack can be launched remotely over the network with low attack complexity, requires privileges but only limited user interaction, and impacts confidentiality, integrity, and availability with a scope change (S:C). Although no known exploits are currently reported in the wild, the medium severity rating (6.5) reflects the tangible risk posed by this vulnerability. The affected product versions include all releases up to and including 1.16.0. The vulnerability was published on October 27, 2025, and no official patches or mitigation links are currently available, emphasizing the need for proactive defensive measures by users of this plugin.

For European organizations, particularly those in education, government, and enterprises leveraging H5P for interactive content delivery, this vulnerability poses a significant risk. Exploitation can lead to unauthorized access to user sessions, leakage of sensitive data, and potential defacement or disruption of web content, undermining trust and compliance with data protection regulations such as GDPR. The ability to execute scripts in the context of other users can facilitate further attacks like phishing or malware distribution. Given the widespread adoption of H5P in European e-learning platforms and digital education initiatives, the impact could be broad, affecting students, educators, and administrative staff. Additionally, compromised systems could be leveraged as pivot points for lateral movement within networks, increasing the overall security risk. The medium severity score suggests that while the vulnerability is serious, it requires some level of privilege and user interaction, somewhat limiting the attack surface but not eliminating the threat.

1. Monitor the vendor’s official channels for patches or updates addressing CVE-2025-62951 and apply them promptly once available. 2. Implement strict input validation and output encoding on all user-generated content fields to prevent malicious script injection. 3. Restrict user privileges to the minimum necessary, limiting the ability to submit or modify interactive content to trusted users only. 4. Employ Content Security Policy (CSP) headers to reduce the impact of potential XSS by restricting the execution of unauthorized scripts. 5. Conduct regular security audits and penetration testing focused on web application input handling and content management components. 6. Educate users and administrators about the risks of XSS and encourage vigilance regarding suspicious content or behavior. 7. Use web application firewalls (WAFs) with rules tuned to detect and block common XSS attack patterns targeting H5P content. 8. Monitor logs and user activity for anomalies that could indicate exploitation attempts or successful attacks.