CVE-2026-49162 in Windows
Summary
by MITRE • 07/14/2026
Use after free in Microsoft Brokering File System allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 07/14/2026
The vulnerability in Microsoft Brokering File System represents a critical use-after-free condition that enables local privilege escalation for authorized attackers. This flaw exists within the file system component responsible for managing brokered file operations, where improper memory management allows an attacker to manipulate freed memory regions and potentially execute arbitrary code with elevated privileges. The issue stems from inadequate validation of file handle references during brokered file operations, creating opportunities for memory corruption that can be exploited to gain SYSTEM-level access.
The technical implementation of this vulnerability involves a race condition in the memory deallocation process where file system operations do not properly validate whether referenced memory has already been freed. When an attacker performs specific file operations through the brokering interface, they can trigger a scenario where a file handle reference remains valid while the underlying memory structure has been reallocated or freed. This creates a use-after-free condition that can be leveraged to overwrite critical memory locations with attacker-controlled data, ultimately enabling privilege escalation.
From an operational perspective, this vulnerability poses significant risk as it requires only local authenticated access to exploit, making it particularly dangerous in environments where users may have legitimate access to systems but should not possess administrative privileges. The attack vector typically involves crafting specific file operations that trigger the memory corruption, followed by exploitation techniques such as heap spraying or return-oriented programming to achieve code execution with elevated privileges. This vulnerability aligns with CWE-416 which specifically addresses use-after-free conditions in software implementations.
The impact of this privilege escalation vulnerability extends beyond immediate system compromise as it allows attackers to bypass normal access controls and potentially establish persistent backdoors within the system. Attackers can leverage this condition to modify system files, create new administrator accounts, or manipulate security settings that would otherwise be restricted to privileged users. The exploitation process typically follows ATT&CK technique T1068 which involves exploiting vulnerabilities in legitimate programs to gain elevated privileges, making this a particularly stealthy attack vector.
Mitigation strategies for this vulnerability include applying Microsoft's security patches promptly, implementing application whitelisting controls to restrict unauthorized file operations, and monitoring for suspicious brokered file system activities. System administrators should also consider implementing privilege separation measures and regularly auditing user access rights to minimize the potential impact of successful exploitation attempts. Additionally, memory protection mechanisms such as address space layout randomization and data execution prevention should be enabled to make exploitation more difficult. The vulnerability demonstrates the importance of proper memory management practices in system-level components and highlights why comprehensive security testing is essential for critical infrastructure software components.