CVE-2025-10117 is a cross-site scripting (XSS) vulnerability identified in version 1.0 of the SourceCodester Simple To-Do List System. The vulnerability exists in the /fetch_tasks.php file, specifically within the Add New Task component. An attacker can exploit this flaw by injecting malicious JavaScript code, such as <script>alert('XSS')</script>, into the input fields processed by this component. Because the input is not properly sanitized or encoded before being reflected back to the user, the malicious script executes in the context of the victim's browser. This vulnerability is remotely exploitable without requiring authentication, although it does require some user interaction (e.g., the victim visiting a crafted URL or viewing a manipulated task list). The CVSS 4.0 base score is 5.1, indicating a medium severity level. The attack vector is network-based with low attack complexity and no privileges required. The impact primarily affects the integrity and confidentiality of user data within the affected application, potentially allowing session hijacking, defacement, or redirection to malicious sites. No patches or official fixes have been published yet, and while the exploit code is publicly available, there are no confirmed reports of active exploitation in the wild. This vulnerability highlights the importance of proper input validation and output encoding in web applications to prevent client-side code injection attacks.

For European organizations using the SourceCodester Simple To-Do List System 1.0, this XSS vulnerability poses risks including unauthorized access to user sessions, theft of sensitive information, and potential compromise of internal web application environments. Since the application is a task management system, it may be used in business or organizational contexts to track sensitive or operational data. Exploitation could lead to data leakage or manipulation, undermining trust and operational integrity. Additionally, successful XSS attacks can serve as a foothold for further attacks such as phishing or malware delivery within corporate networks. The medium severity suggests moderate risk, but the lack of authentication requirements and remote exploitability increase the threat surface. European organizations with limited web application security controls or those that have integrated this system into their workflows without adequate protections are particularly vulnerable. Furthermore, regulatory frameworks such as GDPR impose strict requirements on data protection, and exploitation of this vulnerability could lead to compliance violations and financial penalties.

To mitigate this vulnerability, organizations should implement the following specific measures: 1) Immediately audit and sanitize all user inputs in the /fetch_tasks.php file, especially in the Add New Task component, ensuring that any data reflected in the UI is properly encoded to prevent script execution. 2) Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. 3) Conduct a thorough code review of the entire Simple To-Do List System to identify and remediate any other potential injection points. 4) If possible, isolate the application within a segmented network zone to limit the impact of a successful attack. 5) Monitor web server logs and application behavior for unusual activities indicative of XSS exploitation attempts. 6) As no official patch is currently available, consider replacing or upgrading to a more secure task management solution until a fix is released. 7) Educate users to recognize suspicious links or unexpected prompts that could result from XSS attacks. 8) Implement web application firewalls (WAFs) with rules tailored to detect and block common XSS payloads targeting this application.