CVE-2025-67551 identifies a stored Cross-site Scripting (XSS) vulnerability in the Wappointment plugin developed by the Wappointment team, affecting versions up to and including 2.6.9. The vulnerability stems from improper neutralization of user-supplied input during web page generation, which allows an attacker to inject malicious scripts that are stored and later executed in the context of other users’ browsers. This stored XSS can be exploited by an attacker with low privileges (PR:L) and requires user interaction (UI:R), such as a victim clicking a crafted link or viewing a maliciously crafted page. The vulnerability has a network attack vector (AV:N), meaning it can be exploited remotely over the internet without physical access. The CVSS 3.1 score of 6.5 reflects a medium severity, with partial impact on confidentiality, integrity, and availability (C:L/I:L/A:L). The scope is changed (S:C), indicating that exploitation can affect resources beyond the vulnerable component, potentially impacting the entire web application or user sessions. Although no known exploits are currently reported in the wild, the nature of stored XSS makes it a significant risk for session hijacking, credential theft, defacement, or distribution of malware. Wappointment is a WordPress plugin commonly used for appointment booking, often in healthcare, service industries, and small to medium enterprises. The lack of available patches at the time of disclosure necessitates immediate attention to mitigation strategies. The vulnerability highlights the importance of proper input validation and output encoding in web applications to prevent injection of executable code.

For European organizations, this vulnerability poses a risk to the confidentiality, integrity, and availability of web applications using the Wappointment plugin. Attackers exploiting this stored XSS could hijack user sessions, steal sensitive data such as personal or appointment information, or perform unauthorized actions on behalf of legitimate users. This is particularly critical for sectors like healthcare, legal, and professional services where appointment data is sensitive. The medium severity score indicates a moderate but tangible risk, especially since exploitation requires user interaction and some privileges, which may limit mass exploitation but still allows targeted attacks. The potential for scope change means that the impact can extend beyond the plugin itself, affecting the entire WordPress site and its users. European organizations relying on Wappointment for client interactions or internal scheduling could face reputational damage, regulatory penalties under GDPR if personal data is compromised, and operational disruptions. The absence of known exploits in the wild provides a window for proactive mitigation but should not lead to complacency.

1. Monitor for official patches or updates from the Wappointment team and apply them promptly once released. 2. Implement strict input validation and output encoding on all user-supplied data fields related to appointment booking to prevent injection of malicious scripts. 3. Employ Web Application Firewalls (WAFs) with rules designed to detect and block XSS payloads targeting the Wappointment plugin. 4. Limit user privileges to the minimum necessary, reducing the risk that low-privilege users can inject malicious content. 5. Educate users to be cautious of unsolicited links or content within the application to reduce the risk of user interaction-based exploitation. 6. Conduct regular security audits and penetration testing focusing on web application vulnerabilities, including stored XSS. 7. Consider implementing Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts. 8. Backup data regularly to enable recovery in case of compromise. 9. Review and sanitize existing stored data within Wappointment to remove any malicious scripts that may have been injected previously.