CVE-2026-3766 is a cross-site scripting vulnerability identified in the SourceCodester Web-based Pharmacy Product Management System version 1.0. The vulnerability resides in the edit-profile.php script, where the 'fullname' parameter is improperly sanitized, allowing an attacker to inject arbitrary JavaScript code. This flaw enables remote attackers to craft malicious requests that, when processed by the vulnerable system, execute scripts in the context of the victim's browser. The vulnerability does not require prior authentication, making it accessible to unauthenticated remote attackers. However, exploitation requires some level of user interaction, such as a victim clicking a crafted link or visiting a malicious page that triggers the payload. The CVSS 4.0 base score is 5.1, reflecting medium severity due to the ease of exploitation (network vector, low attack complexity) but limited impact on availability and only partial impact on integrity and confidentiality. The vulnerability could be leveraged to steal session cookies, perform actions on behalf of the user, or redirect users to phishing or malware sites. No official patches have been linked yet, and no active exploits are reported in the wild, but the public release of exploit code increases the urgency for mitigation. The vulnerability highlights the need for proper input validation and output encoding in web applications, especially those handling sensitive healthcare-related data.

The primary impact of CVE-2026-3766 is the compromise of user confidentiality and integrity through the execution of malicious scripts in users' browsers. Attackers can hijack user sessions, steal sensitive information such as authentication tokens, or perform unauthorized actions within the application context. This can lead to data leakage, unauthorized profile changes, or redirection to malicious websites, potentially resulting in further malware infections or phishing attacks. For organizations, this undermines trust in the pharmacy management system, risks patient data exposure, and may lead to regulatory compliance violations, especially in healthcare sectors governed by strict data protection laws. The vulnerability's remote exploitability without authentication broadens the attack surface, increasing the likelihood of exploitation in environments where the affected software is deployed. Although availability impact is minimal, the reputational damage and potential legal consequences can be significant.

To mitigate CVE-2026-3766, organizations should first check for any official patches or updates from SourceCodester and apply them promptly once available. In the absence of patches, implement strict input validation and output encoding on the 'fullname' parameter in edit-profile.php to neutralize any injected scripts. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. Additionally, enable HTTP-only and Secure flags on cookies to reduce the risk of session hijacking. Conduct regular security audits and penetration testing focusing on input handling in web forms. Educate users about the risks of clicking on suspicious links and encourage the use of updated browsers with built-in XSS protections. Where feasible, deploy web application firewalls (WAFs) configured to detect and block XSS attack patterns targeting this parameter. Finally, monitor logs for unusual activities related to profile editing functions to detect potential exploitation attempts early.