CVE-2026-71343 in Windows
Summary
by MITRE • 09/09/2026
Heap-based buffer overflow in Windows Remote Access Connection Manager allows an authorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 09/09/2026
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 specific flaw arises from improper memory management during the processing of certain input data structures associated with these connection configurations. When an attacker provides specially crafted input that exceeds the allocated buffer size in heap memory, it results in a write operation beyond the boundaries of the intended memory block. This overflow can corrupt adjacent heap metadata or overwrite critical function pointers and object headers stored within the same allocation region.
From a technical perspective, this is classified under CWE-122, which denotes a heap-based buffer overflow. The exploitation mechanism typically relies on precise control over the data written to the corrupted memory regions. By carefully crafting the payload, an attacker can manipulate the heap layout to achieve arbitrary code execution upon subsequent operations that interact with the compromised structures. This might involve triggering specific API calls or internal RasMan functions that dereference overwritten pointers. Since the vulnerability resides in a system service running at high privilege levels, successful exploitation grants the attacker significant control over the affected machine. The attack vector is local, meaning it requires an authenticated user to be present on the target system, either physically or through remote access credentials, which aligns with ATT&CK technique T1059, Command and Scripting Interpreter, often used in conjunction with privilege escalation steps following initial code execution.
The operational impact of this vulnerability is severe due to its potential for local privilege escalation and arbitrary code execution. An authorized attacker who exploits this flaw can execute malicious code within the security context of the current user or potentially escalate privileges further depending on the specific configuration and service account permissions associated with RasMan. This could lead to complete system compromise, allowing the installation of malware, exfiltration of sensitive data, modification of system configurations, or creation of persistent backdoors. The presence of this flaw in a core networking component means that any user profile configured for remote access connections is potentially at risk if they can trigger the vulnerable code path through legitimate-looking connection attempts or configuration changes.
Mitigation strategies primarily involve applying vendor-supplied security patches and updates released by Microsoft to address the underlying memory management issues within RasMan. Organizations should ensure that all systems are kept up-to-date with the latest cumulative updates, which often include fixes for such critical vulnerabilities in core Windows components. Additionally, implementing strict access controls and least privilege principles can limit the potential impact if an account is compromised. Network segmentation and monitoring for anomalous behavior related to remote access connections may also help detect exploitation attempts early. Security teams should prioritize patching systems that expose RasMan functionality or have users with elevated privileges who interact frequently with network connection settings, as these represent higher-risk environments susceptible to this type of local privilege escalation attack.