CVE-2025-15483 is a stored cross-site scripting (XSS) vulnerability identified in the Link Hopper plugin for WordPress, maintained by ajferg. The vulnerability exists in all versions up to and including 2.5 and specifically affects multi-site WordPress installations where the 'unfiltered_html' capability is disabled. The root cause is insufficient sanitization and escaping of the 'hop_name' parameter, which allows authenticated users with administrator-level privileges to inject arbitrary JavaScript code into pages generated by the plugin. When other users visit these pages, the injected scripts execute in their browsers, potentially leading to session hijacking, privilege escalation, or unauthorized actions within the WordPress environment. The vulnerability requires the attacker to have administrator-level access, which limits the attack vector but increases the risk if credentials are compromised or insider threats exist. The CVSS v3.1 base score is 4.4, indicating medium severity, with vector metrics AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:N. This means the attack is network exploitable but requires high attack complexity and privileges, no user interaction, and impacts confidentiality and integrity with a scope change. No public exploits are known at this time, and no patches have been linked yet, so mitigation relies on access control and monitoring. The vulnerability is classified under CWE-79, which covers improper neutralization of input during web page generation leading to XSS.

For European organizations, this vulnerability poses a moderate risk primarily to WordPress multi-site environments using the Link Hopper plugin. Exploitation could allow attackers with administrator credentials to execute malicious scripts, potentially leading to theft of sensitive data such as session tokens or user credentials, unauthorized changes to site content, or further compromise of the WordPress environment. This could disrupt business operations, damage reputation, and lead to regulatory non-compliance, especially under GDPR if personal data is exposed. The requirement for administrator-level access reduces the likelihood of external exploitation but increases the risk from insider threats or credential compromise. Organizations running multi-site WordPress installations with this plugin should be particularly vigilant, as multi-site setups are common in large enterprises and hosting providers across Europe. The vulnerability does not affect single-site installations or those with unfiltered_html enabled, limiting the scope somewhat. However, given the widespread use of WordPress in Europe, the potential impact on confidentiality and integrity of web assets is significant enough to warrant prompt attention.

1. Immediately audit all WordPress multi-site installations to identify usage of the Link Hopper plugin, especially versions up to 2.5. 2. Restrict administrator-level access strictly to trusted personnel and enforce strong authentication methods such as multi-factor authentication (MFA). 3. Until an official patch is released, consider disabling or uninstalling the Link Hopper plugin on multi-site installations where feasible. 4. Implement Web Application Firewall (WAF) rules to detect and block suspicious input patterns targeting the 'hop_name' parameter. 5. Monitor logs for unusual administrator activity or unexpected changes in pages generated by the plugin. 6. Educate administrators about the risks of XSS and the importance of input validation and output encoding. 7. Regularly update WordPress core and plugins to the latest versions once a patch for this vulnerability becomes available. 8. Review and adjust the 'unfiltered_html' capability settings to understand their impact on vulnerability exposure. 9. Conduct periodic security assessments and penetration tests focusing on multi-site WordPress configurations. 10. Maintain an incident response plan to quickly address any detected exploitation attempts.