CVE-2026-82312 in OpenVPN
Summary
by MITRE • 09/07/2026
OpenVPN 2.0.0 through 2.6.22 and 2.7_alpha1 through 2.7.6 on Windows allows local authenticated users to cause a denial of service via a NULL DACL on named IPC objects
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Analysis
by VulDB Data Team • 09/07/2026
The vulnerability identified in OpenVPN versions ranging from 2.0.0 through 2.6.22, as well as the alpha and early release branches up to version 2.7.6, represents a significant security flaw within the Windows implementation of the software. This issue specifically affects local authenticated users who possess valid credentials on the host system. The core technical deficiency lies in how OpenVPN handles access control for its Inter-Process Communication (IPC) objects when running on Microsoft Windows operating systems. Specifically, the application creates named IPC objects without properly configuring their security descriptors, resulting in these objects being assigned a NULL Discretionary Access Control List or DACL. In the context of Windows security architecture, a NULL DACL is functionally equivalent to granting unrestricted access to every user and process on the system, including those with minimal privileges such as standard users or potentially unauthenticated entities depending on specific OS configurations and service account permissions.
From a technical perspective, this misconfiguration allows any local authenticated user to interact directly with these IPC objects without restriction. These named pipes or mutexes are critical for OpenVPN's internal operations, facilitating communication between the client daemon and other components of the VPN infrastructure. By exploiting the lack of access restrictions, an attacker can perform unauthorized read or write operations against these channels. The primary manifestation of this vulnerability is a denial of service condition. An adversary can flood these IPC objects with malformed data, excessive connections, or specific sequences that cause the OpenVPN process to crash, hang, or become unresponsive. This effectively disrupts VPN connectivity for all users relying on that instance and potentially destabilizes other services running on the same host if they share dependencies or are affected by system resource exhaustion caused by the attack.
The operational impact of this vulnerability is substantial for organizations deploying OpenVPN in multi-user environments where local user accounts exist alongside privileged service accounts. While the threat actor must first authenticate to the Windows machine, which provides a layer of initial containment, the ease with which they can disrupt services makes it a viable vector for insider threats or compromised low-privilege accounts seeking to cause disruption. The ability to crash the OpenVPN process leads to immediate loss of connectivity for remote users tunneling through that server. In critical infrastructure or enterprise settings where VPN uptime is paramount, this denial of service capability undermines business continuity and operational reliability. Furthermore, if the IPC objects are used in ways that allow data injection beyond simple disruption, there may be secondary risks related to integrity violations, although the primary reported impact remains focused on availability degradation through resource exhaustion or process termination.
This vulnerability aligns with CWE-284, which describes Improper Access Control, specifically highlighting failures in enforcing restrictions on access to resources. It also maps closely to MITRE ATT&CK technique T1565.002, known as Stored Data Manipulation, where an attacker modifies stored data or objects to impact availability. Additionally, the exploitation of IPC mechanisms falls under broader categories of Local Privilege Escalation vectors if the crash leads to unexpected state changes that could be leveraged for further attacks, though in this specific instance, the focus is on denial of service via improper access control. The root cause stems from a failure in secure coding practices during the initialization phase of Windows-specific IPC objects, where developers neglected to apply explicit security descriptors using standard Windows API calls such as SetSecurityInfo or CreateNamedPipe with proper SECURITY_ATTRIBUTES structures that define restrictive DACLs rather than relying on default system behaviors which may be overly permissive.
Mitigation strategies for this vulnerability primarily involve upgrading OpenVPN to a version later than 2.6.22 and 2.7.6, where the developers have addressed the improper handling of IPC object security descriptors. Until an upgrade is feasible, administrators should implement strict network segmentation to limit local access to systems running vulnerable versions of OpenVPN. Additionally, enforcing least-privilege principles for all user accounts on these hosts can reduce the attack surface by ensuring that fewer users possess the necessary authentication credentials to trigger the vulnerability. Monitoring system logs for unusual activity related to named pipe creation or excessive IPC interactions may also aid in early detection of exploitation attempts. Regular patch management and adherence to secure configuration baselines, such as those provided by CIS Benchmarks for Windows services, are essential preventive measures against this class of misconfiguration-based vulnerabilities.