CVE-2026-50458 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 under discussion represents a use-after-free condition within Microsoft's Brokering File System component, which serves as a critical subsystem for managing file operations and access control in Windows environments. This specific flaw exists within the kernel-mode driver responsible for handling file system broker operations, creating a scenario where freed memory regions can be accessed and manipulated by malicious code. The vulnerability is classified as a privilege escalation issue that requires an attacker to already possess valid user credentials within the target system, making it an authorized attack vector rather than a remote exploit.
The technical implementation of this use-after-free flaw occurs when the Brokering File System driver processes certain file operations that involve memory allocation and deallocation sequences. During normal operation, the driver allocates memory structures to manage file access requests and brokered operations between different security contexts. When specific conditions are met during concurrent file operations or when processing malformed input parameters, the driver may free a memory block while references to it remain active in the system's execution path. This creates an opportunity for an attacker to overwrite the freed memory with malicious data, potentially allowing code execution within kernel space where privileges are elevated.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with a pathway to achieve system-level control without requiring network access or complex remote exploitation techniques. Once successfully exploited, the attack vector enables unauthorized users to execute arbitrary code with kernel-level privileges, effectively bypassing standard user-mode security controls and access restrictions that typically protect sensitive system resources. The vulnerability affects multiple Windows versions including Windows 10, Windows 11, and various server editions where the Brokering File System component is present, making it a widespread concern for enterprise environments.
From a cybersecurity perspective, this vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software implementations. The attack pattern follows principles consistent with the ATT&CK framework's privilege escalation techniques, particularly those targeting kernel-mode vulnerabilities and system-level access control bypasses. The exploitability requires local access to the target system, which means attackers must first gain user-level access through other means such as phishing attacks, credential theft, or social engineering before leveraging this specific vulnerability for elevation. Security researchers have noted that the flaw's exploitation is relatively straightforward once an attacker has established a foothold on the system, making it particularly dangerous in environments where user account compromise is possible.
Organizations should implement immediate mitigations including applying Microsoft security updates as soon as they become available, monitoring for suspicious file system operations and kernel-mode activity patterns, and implementing least privilege access controls to limit potential damage from successful exploitation attempts. Additional defensive measures include deploying endpoint detection and response solutions capable of identifying anomalous memory manipulation patterns and ensuring that administrative privileges are not routinely granted to regular user accounts. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date system patches and the necessity of robust security monitoring in protecting against kernel-level exploits that can bypass traditional network-based security controls.