CVE-2025-65368 identifies a Cross Site Scripting (XSS) vulnerability in SparkyFitness version 0.15.8.2. This vulnerability stems from insufficient sanitization of both user-supplied input and outputs generated by integrated large language models (LLMs). XSS vulnerabilities allow attackers to inject malicious scripts into web pages viewed by other users, potentially enabling theft of session tokens, defacement, or redirection to malicious sites. The vulnerability is classified under CWE-79, indicating classic reflected or stored XSS issues. According to the CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N), the attack can be executed remotely over the network without privileges but requires user interaction, such as clicking a crafted link or viewing malicious content. The scope is changed (S:C), meaning the vulnerability affects resources beyond the initially vulnerable component, increasing its impact. Confidentiality and integrity are partially impacted, while availability remains unaffected. No patches or known exploits are currently available, which suggests the vulnerability is newly disclosed and not yet weaponized. The involvement of LLM output in the vulnerability is notable, as it indicates that dynamic content generated by AI models is not properly sanitized, expanding the attack surface. This raises concerns about the security of AI-assisted features in web applications. SparkyFitness is a fitness application, likely used by individuals and organizations for health tracking and wellness management. The vulnerability could be exploited to compromise user data or manipulate displayed information, undermining trust and potentially exposing sensitive personal health information.

For European organizations, the impact of CVE-2025-65368 could be significant in sectors relying on SparkyFitness for employee wellness programs or customer engagement. Successful exploitation could lead to unauthorized disclosure of personal data, including health-related information, violating GDPR and other privacy regulations. The partial compromise of data integrity could result in manipulated fitness data, affecting decision-making or user trust. Although availability is not impacted, the reputational damage and potential regulatory penalties could be substantial. Organizations with large user bases are at higher risk due to the increased likelihood of user interaction with malicious content. The involvement of LLM outputs in the vulnerability also highlights risks in AI-driven features, which are increasingly adopted in European digital services. Attackers could leverage this vulnerability to conduct phishing campaigns or deliver further malware via injected scripts. The lack of available patches means organizations must rely on interim mitigations, increasing operational complexity. Overall, the threat underscores the need for rigorous security controls around AI integrations and user input handling in web applications.

To mitigate CVE-2025-65368, organizations should implement strict input validation and output encoding on all user-supplied data and AI-generated content before rendering it in the browser. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of potential XSS attacks. Monitor application logs and user behavior for signs of exploitation attempts, such as unusual script injections or anomalous user interactions. Until an official patch is released, consider disabling or restricting features that incorporate LLM-generated outputs if feasible. Conduct security testing focused on AI-generated content to identify and remediate similar vulnerabilities proactively. Educate users about the risks of interacting with untrusted links or content within the application. Collaborate with the SparkyFitness vendor to obtain timely updates and apply patches promptly once available. Additionally, review and enhance web application firewalls (WAFs) rules to detect and block XSS payloads targeting this vulnerability. For organizations with compliance obligations, document mitigation efforts and risk assessments to demonstrate due diligence.