CVE-2025-49745 is a cross-site scripting (XSS) vulnerability classified under CWE-79, found in Microsoft Dynamics 365 (on-premises) version 9.1. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages within the application. This flaw enables an attacker to inject malicious scripts that execute in the context of the victim's browser, potentially allowing spoofing attacks such as session hijacking, credential theft, or unauthorized actions performed on behalf of the user. The vulnerability is exploitable remotely over a network without requiring authentication, but it does require user interaction, such as clicking a maliciously crafted link or visiting a compromised webpage. The CVSS v3.1 score is 5.4 (medium severity), reflecting low complexity of attack and limited impact on confidentiality and integrity, with no impact on availability. No known public exploits or patches are currently available, indicating the need for proactive defensive measures. The vulnerability affects Microsoft Dynamics 365 on-premises version 9.1 and earlier versions like 9.0, which are widely used in enterprise environments for customer relationship management and business process automation. Given the critical role of Dynamics 365 in managing sensitive business data, exploitation could lead to unauthorized data disclosure or manipulation, undermining trust and compliance with data protection regulations.

For European organizations, this vulnerability poses a risk primarily to confidentiality and integrity of sensitive business and customer data managed within Microsoft Dynamics 365. Successful exploitation could allow attackers to perform spoofing attacks, potentially leading to session hijacking, unauthorized data access, or manipulation of business records. This could result in financial losses, reputational damage, and regulatory penalties under GDPR due to data breaches. The impact is heightened for sectors relying heavily on Dynamics 365 for critical operations, such as finance, healthcare, manufacturing, and public administration. Since the vulnerability requires user interaction, phishing campaigns could be a likely attack vector, increasing the risk of targeted social engineering attacks. The lack of current patches means organizations must rely on interim mitigations, increasing operational overhead and risk exposure. Additionally, the on-premises deployment model means that organizations are responsible for timely patch management and security controls, which may vary across European entities.

To mitigate CVE-2025-49745, European organizations should implement the following specific measures: 1) Enforce strict input validation and output encoding within customizations or extensions of Dynamics 365 to prevent injection of malicious scripts. 2) Apply web application firewalls (WAFs) with rules designed to detect and block XSS attack patterns targeting Dynamics 365 endpoints. 3) Educate users about phishing and social engineering risks, emphasizing caution with unsolicited links and emails. 4) Restrict browser scripting capabilities where feasible using Content Security Policy (CSP) headers to limit script execution sources. 5) Monitor logs and network traffic for anomalous activities indicative of attempted XSS exploitation. 6) Prepare for rapid deployment of official patches from Microsoft once released by maintaining an up-to-date asset inventory and patch management process. 7) Limit user privileges within Dynamics 365 to the minimum necessary to reduce the impact of potential exploitation. 8) Conduct regular security assessments and penetration testing focusing on web application vulnerabilities. These targeted actions go beyond generic advice by addressing the specific nature of the vulnerability and the operational context of Dynamics 365 on-premises deployments.