CVE-2025-26679 in Windows
Summary
by MITRE • 04/08/2025
Use after free in RPC Endpoint Mapper Service allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 07/09/2025
The vulnerability identified as CVE-2025-26679 represents a critical use-after-free flaw within the Remote Procedure Call Endpoint Mapper service component of Microsoft Windows operating systems. This vulnerability specifically affects the RPC Endpoint Mapper service which is responsible for managing and registering RPC endpoints on Windows systems. The flaw manifests when the service processes certain RPC requests that trigger memory deallocation followed by subsequent access to the freed memory region, creating a potential exploitation vector for privilege escalation attacks.
The technical implementation of this vulnerability stems from improper memory management within the RPC Endpoint Mapper service. When legitimate RPC requests are processed, the service allocates memory structures to handle endpoint registration and lookup operations. However, under specific conditions involving concurrent requests or malformed RPC messages, the service may prematurely free memory resources while other threads or processes continue to reference these locations. This memory management error creates a use-after-free condition that can be exploited by an authenticated local attacker to execute arbitrary code with elevated privileges. The vulnerability specifically impacts systems running Windows 10 versions 2004, 20H2, 21H1, 21H2, and Windows 11 versions 21H2 and 22H2, as well as Windows Server 2019 and 2022.
From an operational perspective, this vulnerability presents a significant risk to enterprise environments as it requires only local authentication to exploit, making it particularly dangerous in scenarios where attackers have gained initial access through other means. The local privilege escalation capability means that even if an attacker initially compromises a system with standard user privileges, they can leverage this vulnerability to gain SYSTEM-level access, effectively bypassing most local security controls. The exploitation process typically involves crafting specific RPC requests that trigger the memory corruption, followed by executing malicious code within the elevated context of the RPC service. This vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software applications, and can be mapped to ATT&CK technique T1068, which covers local privilege escalation through system binary modification or exploitation of service vulnerabilities.
The impact of this vulnerability extends beyond immediate privilege escalation as it can serve as a foundation for further lateral movement within networks. Once an attacker achieves SYSTEM-level access through this vulnerability, they can access all system resources, modify critical system files, install backdoors, and potentially establish persistence mechanisms. The RPC Endpoint Mapper service runs with elevated privileges by design, making it an attractive target for attackers seeking to maximize their access within compromised systems. Organizations should consider this vulnerability as part of a broader attack chain that may begin with initial compromise through phishing, credential theft, or other attack vectors, but where this specific flaw provides the critical privilege escalation necessary for deeper system compromise. The vulnerability's presence in widely deployed Windows versions means that organizations across various sectors, including government, financial services, healthcare, and critical infrastructure, may be at risk and require immediate attention through patch management and security hardening procedures.
Mitigation strategies for CVE-2025-26679 should prioritize immediate patch deployment from Microsoft as the primary defense mechanism, while also implementing additional security controls to reduce the attack surface. Organizations should disable unnecessary RPC services and restrict access to the RPC Endpoint Mapper where possible, particularly on systems where local privilege escalation risks are elevated. Network segmentation and access controls should be implemented to limit local user access to systems running the vulnerable service. Security monitoring should focus on detecting anomalous RPC traffic patterns and unexpected privilege escalation events. Additionally, organizations should consider implementing application whitelisting policies to prevent exploitation of the vulnerability through unexpected code execution paths, and should regularly audit system configurations to ensure that RPC services are properly hardened according to Microsoft security best practices. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security patches and the necessity of robust security monitoring to detect and respond to exploitation attempts.