CVE-2025-4376 is a medium-severity vulnerability identified in Sparx Systems Pro Cloud Server versions earlier than 6.0.165. The issue arises from improper input validation (CWE-20) in the WebEA model search field, which allows an attacker to inject malicious scripts leading to Cross-Site Scripting (XSS). Specifically, the vulnerability enables an unauthenticated remote attacker to execute arbitrary scripts in the context of the victim's browser when they interact with the vulnerable search functionality. The CVSS 4.0 base score of 5.3 reflects a network attack vector with low complexity and no privileges or authentication required, but user interaction is necessary (the victim must use the search field). The impact primarily affects confidentiality by potentially exposing sensitive session information or enabling phishing or session hijacking attacks. Integrity and availability impacts are minimal or not applicable. No known exploits are currently in the wild, and no patches have been linked yet. The vulnerability is notable because Pro Cloud Server is used for collaborative modeling and enterprise architecture management, often containing sensitive organizational data and intellectual property. An attacker exploiting this XSS could target users within the organization to steal credentials or perform further attacks within the trusted environment.

For European organizations using Sparx Systems Pro Cloud Server, this vulnerability poses a risk of client-side attacks that can compromise user sessions and potentially lead to unauthorized access or data leakage. Since the product is used for enterprise architecture and modeling, the exposure of sensitive design and planning information could have strategic consequences. The vulnerability could facilitate spear-phishing campaigns or lateral movement within the network if combined with other attack vectors. Although the vulnerability does not directly compromise server integrity or availability, the indirect effects on confidentiality and trust in the platform can disrupt business operations and decision-making processes. Organizations in sectors with high reliance on secure collaboration and intellectual property protection, such as finance, manufacturing, and government, may face elevated risks. The lack of authentication requirements for exploitation increases the attack surface, especially in environments where the Pro Cloud Server is accessible over the internet or large intranets.

European organizations should prioritize upgrading Sparx Systems Pro Cloud Server to version 6.0.165 or later as soon as it becomes available to address this vulnerability. In the interim, organizations should implement strict input validation and output encoding on the WebEA search field at the application or web server level, if possible, to neutralize malicious scripts. Employing Web Application Firewalls (WAFs) with custom rules to detect and block XSS payloads targeting the search parameter can reduce risk. Additionally, organizations should enforce Content Security Policy (CSP) headers to restrict script execution sources and reduce the impact of any successful XSS attempts. User awareness training should emphasize caution when interacting with search results or links within the Pro Cloud Server interface. Network segmentation and limiting access to the Pro Cloud Server to trusted internal users can reduce exposure. Monitoring logs for unusual input patterns or error messages related to the search functionality can help detect attempted exploitation.