CVE-2026-50305
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 within the Windows operating system. This flaw exists in the way the system handles memory management when processing file broker requests, creating an opportunity for malicious exploitation that can lead to local privilege escalation. The vulnerability specifically affects the manner in which the system releases and reuses memory locations, allowing an attacker to manipulate freed memory regions and potentially execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability stems from improper handling of reference counting and memory deallocation within the file brokering infrastructure. When legitimate file operations are processed through the broker, the system allocates memory structures to manage these requests and their associated metadata. However, a race condition or improper cleanup mechanism allows an attacker to trigger the release of memory while still maintaining references to it, creating a scenario where subsequent allocations might reuse the same memory addresses. This use-after-free condition can be exploited through carefully crafted file operations that leverage the broker to force specific memory states. According to CWE-416, this represents a classic use-after-free vulnerability where memory is accessed after it has been freed, potentially leading to arbitrary code execution.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it can be leveraged by attackers who have already established a foothold on a target system. The local privilege escalation capability means that an attacker with minimal user-level access could potentially gain SYSTEM-level privileges, enabling them to bypass security controls, modify system files, or establish persistent access. This type of vulnerability is particularly dangerous because it requires no special network access or complex attack vectors beyond local execution capabilities. The exploitation process typically involves creating specific file operations that trigger the memory management flaw, followed by careful manipulation of the freed memory to achieve code execution. Such vulnerabilities align with ATT&CK technique T1068 which covers 'Local Privilege Escalation' and specifically addresses the abuse of system-level vulnerabilities.
Mitigation strategies for this vulnerability should focus on both immediate remediation and long-term defensive measures. Microsoft has released security updates that address the specific memory management issues within the Brokering File System, and administrators should prioritize applying these patches to all affected systems. Additionally, organizations can implement enhanced monitoring for suspicious file broker activities and memory allocation patterns that might indicate exploitation attempts. The use of exploit prevention technologies such as control flow integrity, address space layout randomization, and application whitelisting can provide additional layers of defense. Security teams should also conduct regular vulnerability assessments to identify similar memory management issues in other system components and implement proper code review processes that focus on memory handling patterns. Organizations may consider implementing just-in-time compilation restrictions and runtime protections for file broker operations to reduce the attack surface and prevent successful exploitation attempts.