CVE-2026-84012 in Windows
Summary
by MITRE • 10/14/2026
Double free in Remote Desktop Gateway Service allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described involves a critical memory management error within the Microsoft Remote Desktop Gateway service, specifically classified as a double-free condition. This type of flaw occurs when a program attempts to deallocate or release a block of memory that has already been freed by another part of the application or in a previous operation. In the context of network-facing services like the Remote Desktop Gateway, such errors are particularly dangerous because they can be triggered remotely without requiring any prior authentication on the target system. The vulnerability resides deep within the service's handling of specific protocol requests, where improper tracking of memory pointers allows an attacker to manipulate the heap structure during request processing.
From a technical perspective, this flaw is categorized under CWE-415, which defines Double Free as a weakness resulting from freeing memory that has already been freed. This action corrupts the internal data structures used by the operating system's memory manager, such as the free list or metadata headers associated with heap chunks. When an attacker sends specially crafted network packets to the Remote Desktop Gateway service, they can exploit this race condition or logic error to force the application to release the same memory address twice. This corruption destabilizes the process state and creates opportunities for arbitrary code execution by allowing the attacker to control what data is written into the corrupted memory regions during subsequent allocation operations.
The operational impact of this vulnerability is severe, as it enables an unauthenticated remote attacker to execute arbitrary code on the vulnerable system with the privileges of the Remote Desktop Gateway service account. This typically means SYSTEM-level access if the service runs under local system credentials, which are common in Windows Server environments. Once code execution is achieved, the attacker can install programs, view, change, or delete data, and create new accounts with full user rights. Furthermore, because this vulnerability affects a core infrastructure component responsible for managing remote desktop connections across network boundaries, it poses a significant risk to enterprise security architectures that rely on RD Gateway for secure access control.
This exploit scenario aligns closely with MITRE ATT&CK techniques related to Initial Access and Execution via Remote Services. Specifically, it falls under the category of exploiting services that are exposed to untrusted networks without proper authentication requirements. The ability to execute code remotely over a network makes this vulnerability highly attractive for automated worm-like propagation or targeted attacks against organizations using RD Gateway as their primary remote access solution. Attackers can leverage tools and frameworks designed for heap exploitation techniques, such as heap spraying or arbitrary write primitives derived from the double-free state, to achieve persistent control over compromised hosts.
Mitigation strategies must focus on immediate patching and network-level controls. Organizations should apply the latest security updates provided by Microsoft that address this specific memory corruption issue in the Remote Desktop Gateway service. Until patches are applied, it is advisable to restrict access to the RD Gateway port (typically TCP 443) using firewalls or intrusion prevention systems to limit exposure only to trusted IP addresses and subnets. Additionally, implementing strict network segmentation can help contain potential lateral movement if a system were compromised. Regular vulnerability scanning focused on unpatched remote services is essential for maintaining visibility into this risk vector within the enterprise environment.