CVE-2026-83952 in Windows
Summary
by MITRE • 09/09/2026
Heap-based buffer overflow in Windows Resilient File System (ReFS) allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability described involves a heap-based buffer overflow within the Microsoft Windows Resilient File System, commonly known as ReFS. This component is responsible for managing file system operations on volumes formatted with ReFS, which is designed primarily for data integrity and scalability in enterprise environments. The specific flaw arises from improper memory management during the processing of certain file system requests or metadata structures. When an attacker provides specially crafted input that exceeds the allocated buffer size on the heap, it causes adjacent memory regions to be overwritten. This type of error is classified under CWE-122, which denotes a heap-based buffer overflow where data written beyond the bounds of a dynamically allocated block can corrupt internal data structures or overwrite critical control information such as function pointers and return addresses.
The operational impact of this vulnerability is severe because it allows for local privilege escalation. An attacker who has already gained access to the system with limited user privileges, such as a standard authenticated user, can exploit this memory corruption issue to execute arbitrary code in the context of higher-privileged accounts or even the operating system kernel itself. By carefully crafting the overflow payload, an adversary can manipulate the execution flow of the ReFS driver or related components, potentially gaining SYSTEM-level access. This effectively bypasses Windows security boundaries and allows full control over the affected machine, enabling further lateral movement within a network, installation of malware, exfiltration of sensitive data, or modification of system configurations to maintain persistence.
From an offensive security perspective, this vulnerability aligns with MITRE ATT&CK techniques related to privilege escalation via local exploits. Specifically, it relates to T1068 Exploitation for Privilege Escalation and potentially T1055 Process Injection if the exploit involves injecting code into a privileged process running in memory. The attack vector is classified as Local (T1059), requiring physical or logical access to the target system prior to exploitation. Because ReFS operates at a low level within the operating system, successful exploitation often requires bypassing modern mitigations such as Data Execution Prevention and Address Space Layout Randomization, although these defenses may be circumvented through advanced heap grooming techniques that are well-documented in contemporary exploit development literature.
Mitigation strategies for this vulnerability primarily involve applying the relevant security updates provided by Microsoft to patch the underlying code flaw within the ReFS driver components. Organizations should ensure that all systems utilizing ReFS volumes have the latest cumulative updates installed, as these patches typically include bounds checking and input validation improvements that prevent the buffer overflow condition from occurring. In environments where immediate patching is not feasible due to compatibility concerns, network segmentation can help limit exposure by restricting access to critical file servers hosting ReFS volumes to only authorized administrative accounts. Additionally, enforcing strict least-privilege policies ensures that even if an attacker compromises a lower-level account, the potential impact of exploiting this vulnerability remains contained until proper remediation steps are executed.