CVE-2026-3302 identifies a cross-site scripting vulnerability in SourceCodester Doctor Appointment System version 1.0, specifically within the /register.php script handling the Sign Up Page. The vulnerability arises from improper input validation and sanitization of the Email parameter, which allows an attacker to inject arbitrary JavaScript code. When a victim interacts with a maliciously crafted input—such as clicking a link or submitting a form containing the injected script—the attacker’s code executes in the victim’s browser context. This can lead to session hijacking, credential theft, or unauthorized actions performed on behalf of the user. The vulnerability is remotely exploitable without requiring authentication, increasing its risk profile. Although no active exploits have been reported in the wild, the availability of proof-of-concept code lowers the barrier for attackers to develop functional exploits. The vulnerability does not affect the availability of the system but compromises confidentiality and integrity to some extent. The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges or user interaction required for the attacker, but user interaction is needed for the victim, and limited impact on integrity. The absence of patches or vendor advisories at this time necessitates immediate mitigation through input validation and output encoding best practices.

The primary impact of CVE-2026-3302 is on the confidentiality and integrity of user data within the affected Doctor Appointment System. Successful exploitation can allow attackers to execute arbitrary scripts in the context of the victim’s browser, potentially leading to theft of session cookies, personal information, or credentials. This can facilitate further attacks such as account takeover or unauthorized access to sensitive patient data. While the vulnerability does not directly affect system availability, the resulting compromise can damage organizational reputation, violate patient privacy regulations, and lead to compliance penalties. Healthcare organizations relying on this system may face increased risk of targeted phishing or social engineering attacks leveraging the XSS vulnerability. The remote exploitability and lack of required privileges make this a viable vector for attackers seeking to compromise user trust and data integrity in medical appointment environments.

To mitigate CVE-2026-3302, organizations should implement strict input validation on the Email parameter within /register.php, ensuring that only properly formatted email addresses are accepted. Employing server-side validation in addition to client-side checks is critical. Output encoding or escaping should be applied to all user-supplied data before rendering it in HTML contexts to prevent script execution. Utilizing security libraries or frameworks that automatically handle XSS protection can reduce human error. Web application firewalls (WAFs) can provide an additional layer of defense by detecting and blocking malicious payloads targeting this parameter. Organizations should monitor for suspicious activity related to user registration and educate users about the risks of interacting with untrusted links. Finally, contacting the vendor or community maintaining the SourceCodester Doctor Appointment System to request or develop an official patch is recommended to ensure long-term security.