CVE-2026-1147 identifies a Cross Site Scripting (XSS) vulnerability in the Patients Waiting Area Queue Management System version 1.0 developed by SourceCodester/Patrick Mvuma. The vulnerability is located in the /php/api_patient_schedule.php endpoint, where the 'Reason' parameter is improperly sanitized, allowing attackers to inject malicious JavaScript code. This injection can be performed remotely without authentication, although exploitation requires user interaction to execute the payload in the victim's browser context. The vulnerability impacts the confidentiality and integrity of user sessions by potentially enabling session hijacking, credential theft, or unauthorized actions performed on behalf of the user. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:L), and user interaction required (UI:P), with no impact on availability but limited impact on confidentiality and integrity. No official patches or fixes have been released, and no known exploits are currently active in the wild. The vulnerability is significant for healthcare environments where patient queue management systems are critical for operational efficiency and data privacy. Attackers exploiting this vulnerability could disrupt patient scheduling, manipulate queue data, or steal sensitive patient information via injected scripts. The lack of input validation and output encoding in the affected parameter is the root cause. Remediation requires developers to implement proper input sanitization, output encoding, and security headers to mitigate script injection risks.

For European organizations, particularly those in the healthcare sector, this vulnerability poses a risk to patient data confidentiality and the integrity of patient scheduling processes. Exploitation could lead to unauthorized access to session tokens or credentials, enabling attackers to impersonate users or manipulate queue data, potentially causing operational disruptions. Although the vulnerability does not directly affect system availability, the indirect effects of compromised patient management could degrade service quality and trust. Given the sensitivity of healthcare data under GDPR, exploitation could also result in regulatory penalties and reputational damage. The remote exploitability without authentication increases the attack surface, especially for publicly accessible queue management portals. Organizations relying on this specific version of the SourceCodester system or similar queue management solutions are at risk of targeted phishing or drive-by attacks leveraging this XSS flaw. The medium severity rating reflects the moderate but non-trivial impact on confidentiality and integrity, combined with the ease of exploitation and lack of current patches.

To mitigate this vulnerability, organizations should immediately audit and sanitize all user inputs, particularly the 'Reason' parameter in the /php/api_patient_schedule.php endpoint, using strict whitelist validation and context-appropriate output encoding. Implementing Content Security Policy (CSP) headers can help restrict the execution of unauthorized scripts. Web Application Firewalls (WAFs) should be configured to detect and block suspicious payloads targeting this parameter. Regular security testing, including automated scanning and manual code reviews, should be conducted to identify similar injection points. Since no official patch is available, organizations should consider isolating or restricting access to the affected system until remediation is applied. User awareness training to recognize phishing or suspicious links can reduce the risk of user interaction exploitation. Monitoring logs for unusual activity related to the vulnerable endpoint can provide early detection of attempted attacks. Finally, organizations should engage with the vendor or community to obtain or develop patches and update the system promptly once fixes are available.