CVE-2026-36324: XSS in SourceCodester Doctor Appointment System 1.0 – Patch & Detection

Technical summary

CVE-2026-36324 is a reflected or stored XSS vulnerability (CWE-79) in the register.php file of SourceCodester Doctor Appointment System 1.0. The application fails to properly sanitize and escape user-supplied input during the registration process, allowing attackers to inject arbitrary JavaScript. The CVSS v3.1 score of 6.1 (Medium) reflects that exploitation requires user interaction but can affect confidentiality and integrity across scope boundaries. The network-accessible registration endpoint and lack of input validation create a straightforward attack surface.

Business impact

Organizations deploying this appointment system face potential compromise of user accounts and sensitive patient data. Attackers exploiting this XSS can harvest login credentials, modify appointment records, exfiltrate protected health information (PHI), or impersonate healthcare staff. The healthcare context amplifies reputational and regulatory risk, particularly under HIPAA compliance requirements. End-user trust in the platform will be eroded if account takeovers or unauthorized access become apparent.

Affected systems

SourceCodester Doctor Appointment System version 1.0 is affected. The vulnerability exists specifically in the register.php registration functionality. Any deployment of this version handling real patient or staff accounts is at risk. Verify your installed version against the vendor's advisory to confirm whether you are running the affected 1.0 release.

Exploitability

Exploitation is straightforward and does not require authentication or special privileges. An attacker crafts a malicious registration link or form containing XSS payloads and tricks a user into visiting it—a common social engineering vector. User interaction (clicking the link, submitting the form) is required, which is typically easy to achieve in targeted attacks or mass campaigns. No advanced exploit techniques or zero-day sophistication are needed; standard XSS payloads apply.

Remediation

The primary remediation is to upgrade to a patched version of SourceCodester Doctor Appointment System if one is available from the vendor. Verify the vendor's advisory for specific version numbers and release dates. If no patch exists, implement input validation and output encoding in register.php: validate all user inputs server-side, reject or sanitize script tags and special characters, and HTML-encode all output displayed in the browser. Deploy a Web Application Firewall (WAF) rule set to detect and block common XSS patterns as a temporary compensating control.

Patch guidance

Check SourceCodester's official website or GitHub repository for updated versions of the Doctor Appointment System released after the vulnerability disclosure (2026-05-29). Apply the latest stable release to all affected instances. Test the patched version in a staging environment before production deployment to ensure no breaking changes to appointment workflows or data. Verify that the patch addresses input sanitization in register.php and other user-input endpoints.

Detection guidance

Monitor application logs for suspicious patterns in registration requests, such as angle brackets, script tags, event handlers (onclick, onerror), or JavaScript keywords in form fields. Review web server access logs for registration submissions containing encoded XSS payloads. Implement browser-based security monitoring to detect injected scripts executing in user sessions. Conduct regular user-interaction-based testing by submitting harmless XSS payloads (e.g., <img src=x onerror=alert()>) to the registration form and confirming they are either rejected or safely encoded in responses.

Why prioritize this

Although the CVSS score is Medium (6.1), this vulnerability warrants prompt attention in a healthcare context. Patient data sensitivity, regulatory compliance obligations, and the ease of exploitation via a public registration interface make this a higher operational priority than the numeric score alone suggests. Prioritize patching or compensating controls within 30–60 days.

Risk score, explained

The CVSS v3.1 score of 6.1 reflects a Medium severity assessment based on: (1) network-accessible attack vector requiring no authentication, (2) low complexity (standard XSS techniques), (3) required user interaction, (4) change of scope (JavaScript can affect the entire application context), and (5) low impact to confidentiality and integrity (session hijacking, data viewing, minor modifications rather than deletion or system-wide compromise). The score does not account for healthcare-specific risk amplification, regulatory penalties, or patient data sensitivity, which may justify a higher internal risk rating.

Frequently asked questions