CVE-2026-3302 Overview
A Cross-Site Scripting (XSS) vulnerability has been identified in SourceCodester Doctor Appointment System version 1.0. The vulnerability exists in the /register.php file within the Sign Up Page component. An attacker can exploit this flaw by manipulating the Email argument to inject malicious scripts, which can then be executed in the context of a victim's browser session. The attack can be launched remotely without authentication, and a proof-of-concept exploit has been made publicly available.
Critical Impact
Remote attackers can inject arbitrary scripts into the application, potentially leading to session hijacking, credential theft, or malicious actions performed on behalf of authenticated users.
Affected Products
- SourceCodester Doctor Appointment System 1.0
- remyandrade doctor_appointment_system
Discovery Timeline
- 2026-02-27 - CVE CVE-2026-3302 published to NVD
- 2026-02-27 - Last updated in NVD database
Technical Details for CVE-2026-3302
Vulnerability Analysis
This vulnerability is classified as CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The vulnerable component is the registration functionality located in /register.php, specifically within the Sign Up Page. The application fails to properly sanitize user-supplied input in the Email field before rendering it back to users, creating an injection point for malicious scripts.
The vulnerability allows attackers to inject arbitrary JavaScript code that executes in the browser context of users who view the affected page. This can result in theft of session cookies, redirection to malicious sites, defacement of the web application, or phishing attacks against application users.
Root Cause
The root cause is improper input validation and output encoding in the registration form processing logic. The Email parameter is accepted and reflected in the HTML response without adequate sanitization or encoding. This allows attackers to break out of the expected HTML context and inject executable script content.
Attack Vector
The attack is network-based and can be executed remotely. An attacker crafts a malicious payload containing JavaScript code and submits it through the Email field in the registration form. When this data is rendered in the application, the malicious script executes in the victim's browser.
The vulnerability requires user interaction (a victim must visit the page containing the injected payload) but does not require authentication to exploit. A publicly available proof-of-concept demonstrates the exploitation technique, as documented in the GitHub PoC Repository.
Detection Methods for CVE-2026-3302
Indicators of Compromise
- Unusual JavaScript code appearing in Email field values in application logs
- HTTP requests containing encoded script tags (%3Cscript%3E) or event handlers (onerror, onload) in the Email parameter
- Reports of unexpected pop-ups or redirections from users interacting with the registration page
Detection Strategies
- Implement Web Application Firewall (WAF) rules to detect XSS payloads in form submissions targeting /register.php
- Monitor application logs for Email field entries containing HTML tags or JavaScript event handlers
- Deploy browser-based XSS detection mechanisms such as Content Security Policy (CSP) violation reporting
Monitoring Recommendations
- Enable detailed logging for all form submissions to the /register.php endpoint
- Configure alerts for patterns matching common XSS payloads in user input fields
- Review access logs for unusual activity patterns targeting the Sign Up Page
How to Mitigate CVE-2026-3302
Immediate Actions Required
- Implement strict input validation on the Email field to allow only valid email address formats
- Apply context-appropriate output encoding when displaying user-supplied data in HTML pages
- Deploy Content Security Policy (CSP) headers to prevent inline script execution
- Consider temporarily disabling the registration functionality until a patch is applied
Patch Information
No official vendor patch is currently available for this vulnerability. The application is distributed through SourceCodester, and users should monitor for updates. Additional vulnerability details are available through VulDB Entry #348053.
Workarounds
- Implement server-side input sanitization using established security libraries to strip or encode HTML special characters
- Deploy a Web Application Firewall (WAF) with XSS filtering rules in front of the application
- Add client-side validation as a defense-in-depth measure (not a primary control)
- Consider implementing HTTPOnly and Secure flags on session cookies to limit XSS impact
# Example Apache configuration for Content Security Policy header
# Add to .htaccess or Apache virtual host configuration
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
