CVE-2025-49693 in Windows
Summary
by MITRE • 07/08/2025
Double free in Microsoft Brokering File System allows an authorized attacker to elevate privileges locally.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 06/03/2026
The vulnerability in Microsoft Brokering File System represents a critical double free error that enables local privilege escalation for authorized attackers. This flaw exists within the file system's memory management operations where improper handling of memory allocation and deallocation routines creates opportunities for attackers to manipulate the system's heap structure. The vulnerability specifically manifests when the system processes certain file operations that involve multiple memory deallocations of the same memory block, creating conditions where attacker-controlled data can be used to manipulate heap metadata and execute arbitrary code with elevated privileges. The double free condition occurs at the kernel level within the brokering file system component, which serves as an intermediary layer for file system operations and is responsible for managing file access controls and resource allocation. This type of vulnerability falls under the common weakness enumeration CWE-415, which specifically addresses double free conditions in memory management. The attack vector requires an authenticated user account with access to the system, making it particularly dangerous as it leverages legitimate user privileges to escalate to system-level access. The operational impact extends beyond simple privilege escalation, as successful exploitation can lead to complete system compromise and persistent access to sensitive data and resources. Attackers can exploit this vulnerability by crafting specific file operations that trigger the double free condition, potentially allowing them to execute malicious code with kernel-level privileges. The exploitation process typically involves memory corruption techniques that manipulate heap structures to redirect execution flow, often utilizing return-oriented programming or other advanced exploitation methods. Microsoft's brokering file system component operates at a critical layer of the operating system, making this vulnerability particularly severe as it sits between user applications and core system resources. The attack follows patterns consistent with the attack technique T1068 in the MITRE ATT&CK framework, which covers privilege escalation through local exploitation of system vulnerabilities. The vulnerability's severity is amplified by the fact that it requires minimal user privileges to exploit, making it accessible to any authenticated user who can perform file operations within the system. Organizations should prioritize immediate patching of this vulnerability as it represents a significant risk to system integrity and data security. The exploitation of this double free condition can result in persistent backdoor access, data exfiltration, and complete compromise of the affected system. Security teams must implement comprehensive monitoring for suspicious file operations and memory allocation patterns that could indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper memory management in kernel-level components and highlights the need for rigorous code review processes that identify potential heap corruption issues. Mitigation strategies should include not only patch deployment but also enhanced system monitoring and user access controls to limit potential exploitation pathways. The presence of such vulnerabilities in core operating system components underscores the necessity of maintaining up-to-date security patches and implementing defense-in-depth strategies that provide multiple layers of protection against privilege escalation attacks.