CVE-2025-60304 identifies a Cross Site Scripting (XSS) vulnerability in the Simple Scheduling System version 1.0 developed by code-projects. The vulnerability arises from insufficient sanitization or encoding of user input in the Subject Description field, allowing attackers to inject arbitrary client-side scripts. When a user views the affected field, the malicious script executes within their browser context, potentially leading to session hijacking, theft of authentication tokens, or unauthorized actions performed on behalf of the user. This type of vulnerability exploits the trust a user places in the web application and can be leveraged for phishing, spreading malware, or pivoting to further attacks within the network. The vulnerability was reserved on September 26, 2025, and published on October 9, 2025, but no CVSS score or patch links are currently available, and no known exploits have been reported in the wild. The absence of a CVSS score suggests the vulnerability is newly disclosed and may not yet have widespread exploitation. The affected product is a scheduling system, which is often used in organizational environments to manage appointments, meetings, or resource allocation, making it a potential target for attackers seeking to disrupt operations or gain unauthorized access. The lack of version specifics beyond 1.0 limits precise scope assessment, but the vulnerability's presence in a scheduling system implies potential exposure in environments where this software is deployed, including corporate, educational, or governmental institutions.

For European organizations, exploitation of this XSS vulnerability could lead to significant risks including unauthorized access to user sessions, data leakage, and potential compromise of internal systems if attackers leverage stolen credentials or session tokens. Scheduling systems often integrate with email, calendar, and resource management tools, so a successful attack could disrupt business operations, cause reputational damage, and lead to compliance issues under regulations like GDPR if personal data is exposed. The impact is heightened in sectors where scheduling systems coordinate critical activities, such as healthcare, transportation, or public administration. While no active exploits are known, the vulnerability's presence in a widely used scheduling tool could attract attackers aiming to exploit less monitored or legacy systems. The lack of authentication requirements for triggering the XSS (assuming the Subject Description field is user-editable and viewable by others) increases the attack surface. However, the impact is somewhat limited by the need for user interaction (victims must view the malicious content), which may reduce the scale of automated exploitation but still poses a serious risk in targeted attacks.

To mitigate CVE-2025-60304, organizations should implement strict input validation and output encoding on the Subject Description field to neutralize malicious scripts. Specifically, applying context-aware encoding (e.g., HTML entity encoding) before rendering user input in the browser is critical. If source code access is available, developers should update the application to sanitize inputs using established libraries or frameworks that handle XSS protection. In the absence of an official patch, organizations can deploy Web Application Firewalls (WAFs) with custom rules to detect and block suspicious payloads targeting the Subject Description field. Additionally, security teams should monitor logs for unusual activity or error messages related to script injection attempts. User education is important to recognize phishing or suspicious links that might exploit this vulnerability. Regular security assessments and penetration testing should include checks for XSS vulnerabilities in scheduling and related systems. Finally, organizations should track updates from the vendor or security advisories for patches or official mitigations.