CVE-2025-49745 in Dynamics 365
Summary
by MITRE • 08/12/2025
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Dynamics 365 (on-premises) allows an unauthorized attacker to perform spoofing over a network.
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Analysis
by VulDB Data Team • 08/16/2025
This vulnerability represents a critical cross-site scripting flaw in Microsoft Dynamics 365 on-premises deployments that stems from inadequate input sanitization during web page generation processes. The weakness manifests when the application fails to properly neutralize user-supplied data before incorporating it into dynamically generated web content, creating an attack vector that enables malicious actors to inject malicious scripts into web pages viewed by other users. This specific vulnerability falls under the CWE-79 category of Cross-Site Scripting, which is classified as a fundamental web application security flaw that has been consistently identified as one of the most prevalent security weaknesses in web applications. The attack surface is particularly concerning in on-premises deployments where organizations maintain direct control over their infrastructure but may lack the rapid security response capabilities of cloud-based solutions.
The operational impact of this vulnerability extends beyond simple script injection, as it enables sophisticated spoofing attacks that can compromise user sessions and data integrity. Attackers can leverage this weakness to manipulate web page content in real-time, potentially redirecting users to malicious sites, stealing session cookies, or executing unauthorized actions within the context of the victim's browser session. The network-based nature of the attack means that exploitation can occur without requiring physical access to the target system, making it particularly dangerous for enterprise environments where Dynamics 365 serves as a central business application. This vulnerability specifically targets the web generation pipeline of Microsoft Dynamics 365, which processes user input through various forms, reports, and interactive components that render dynamic content. The flaw can be exploited through multiple vectors including form submissions, URL parameters, and data inputs that are not properly sanitized before being rendered in web interfaces.
Organizations utilizing Microsoft Dynamics 365 on-premises deployments face significant risk exposure from this vulnerability, as it directly undermines the trust model that enterprise applications rely upon for secure user interactions. The attack can result in unauthorized data access, session hijacking, and potential privilege escalation within the application environment. Security professionals should note that this vulnerability aligns with ATT&CK technique T1566.001 for Phishing and T1071.001 for Application Layer Protocol, as attackers can craft malicious payloads that appear legitimate to users while exploiting the XSS weakness. The remediation approach requires immediate implementation of proper input validation and output encoding mechanisms throughout the application's web generation pipeline, with particular attention to how user data flows through the system before being rendered in browser contexts. Organizations should implement comprehensive security testing procedures including dynamic application security testing and manual penetration testing to identify similar weaknesses in their deployment environments.
Microsoft has issued security updates to address this vulnerability, and administrators should prioritize applying the relevant patches to their on-premises installations. The fix typically involves implementing robust input sanitization routines and ensuring that all user-supplied data is properly escaped before being incorporated into web page content. Additional protective measures include implementing content security policies, deploying web application firewalls, and establishing monitoring procedures to detect anomalous user behavior patterns that might indicate exploitation attempts. Security teams should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation. The vulnerability demonstrates the critical importance of maintaining secure coding practices and regular security assessments in enterprise application environments, particularly for mission-critical systems like Microsoft Dynamics 365 that handle sensitive business data and user information. Organizations should conduct thorough risk assessments to determine the potential impact on their specific deployments and implement layered defensive strategies to protect against similar vulnerabilities in other applications within their environment.