CVE-2026-85867 in Windows
Summary
by MITRE • 10/14/2026
Heap-based buffer overflow in Windows Remote Access Connection Manager allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described involves a heap-based buffer overflow within the Windows Remote Access Connection Manager, commonly referred to as RasMan. This component is responsible for managing remote access connections on Microsoft Windows operating systems, handling tasks such as establishing and maintaining dial-up, VPN, and other network connection profiles. The presence of this flaw in a core system service highlights a critical security gap that can be exploited by attackers who have already gained initial access to the target machine. Because the vulnerability resides within a privileged system process, successful exploitation allows an attacker to execute arbitrary code with elevated privileges, effectively bypassing standard user-level restrictions and gaining control over the underlying operating system.
From a technical perspective, heap-based buffer overflows occur when data is written beyond the allocated boundaries of a memory block on the heap. In the context of RasMan, this likely stems from improper validation or bounds checking of input parameters passed to functions that manage connection configurations or network packet processing. When an authorized attacker interacts with the service, they can supply specially crafted inputs that exceed the expected buffer size. This overflow overwrites adjacent memory structures, potentially including function pointers or object headers within the heap metadata. By carefully controlling these overwritten values, an attacker can redirect program execution flow to malicious shellcode injected into the process memory, thereby achieving arbitrary code execution in the context of the SYSTEM account or other high-privilege service accounts associated with RasMan.
The operational impact of this vulnerability is severe due to its potential for local privilege escalation. An authorized user on the system, who might otherwise be limited by standard security policies such as User Account Control (UAC) or group policy restrictions, can leverage this flaw to escalate their privileges to that of an administrator or even SYSTEM level access. This transformation from a low-privileged account to a high-privilege one enables the attacker to install persistent backdoors, create new administrative accounts, modify security settings, and access sensitive data stored on the local machine. Furthermore, once full control is achieved, the compromised system can be used as a pivot point for lateral movement within an enterprise network, significantly expanding the blast radius of the initial breach.
This vulnerability aligns with CWE-122, which categorizes heap-based buffer overflows, and maps to MITRE ATT&CK techniques related to privilege escalation via local exploits or binary exploitation. Specifically, it relates to Tactic 6: Credential Access and Tactic 7: Privilege Escalation within the attack lifecycle. The ability to execute code in a privileged context allows attackers to bypass many standard detection mechanisms that focus on external network threats rather than internal process manipulation. Consequently, this represents a significant risk for organizations relying on Windows-based infrastructure for remote access services, as it undermines the principle of least privilege and compromises the integrity of the host system.
Mitigation strategies must prioritize immediate patching through official Microsoft security updates designed to address flaws in RasMan. Administrators should ensure that all systems running vulnerable versions of Windows are updated with the latest cumulative patches released by Microsoft. In environments where patching is not immediately feasible, network segmentation can help limit exposure by restricting access to remote access services from untrusted networks. Additionally, implementing strict application control policies and monitoring for unusual process behavior or memory allocation patterns associated with RasMan can aid in early detection of exploitation attempts. Security teams should also review user accounts with local administrative rights to minimize the attack surface available to potential insiders or compromised credentials. Regular audits of system configurations and adherence to hardening guidelines such as those provided by CIS Benchmarks will further reduce the likelihood of successful exploitation.