CVE-2025-50054 is a heap-based buffer overflow vulnerability identified in the OpenVPN ovpn-dco-win kernel driver component, affecting versions 1.3.0 and earlier as well as 2.5.8 and earlier. This vulnerability arises when a local user process sends an oversized control message buffer to the kernel driver, which fails to properly validate the buffer size before processing. The improper handling leads to a heap-based buffer overflow condition, which can corrupt memory and cause the system to crash (denial of service). Since the vulnerability is triggered by a local user process, exploitation requires local access to the affected Windows system. The vulnerability impacts the kernel-mode driver component of OpenVPN's Data Channel Offload (DCO) implementation on Windows, which is designed to improve VPN performance by offloading packet processing to the kernel. The overflow occurs due to inadequate bounds checking on control message buffers passed from user space to kernel space, a classic CWE-122 (Heap-based Buffer Overflow) issue. There are no known exploits in the wild at the time of publication, and no patches or fixes have been linked yet. The lack of a CVSS score indicates that the vulnerability is newly disclosed and has not yet undergone formal severity assessment. The vulnerability primarily results in system crashes, impacting availability, but given its kernel-level nature, it could potentially be leveraged for privilege escalation or arbitrary code execution if combined with other vulnerabilities or techniques, although such exploitation is not confirmed. The vulnerability does not require user interaction beyond local process execution, and remote exploitation is not possible without prior local access.

For European organizations, the primary impact of CVE-2025-50054 is the potential for denial of service on Windows systems running vulnerable versions of OpenVPN ovpn-dco-win. This could disrupt VPN connectivity, impacting remote access, secure communications, and business continuity, especially for organizations relying heavily on OpenVPN for secure remote work or inter-office connectivity. While the vulnerability requires local access, insider threats or compromised endpoints could exploit this to cause system instability or crashes. Given the kernel-level nature of the vulnerability, there is a risk that attackers with local access could escalate privileges or execute arbitrary code, potentially leading to broader system compromise. This risk is particularly relevant for critical infrastructure, government agencies, financial institutions, and enterprises with sensitive data and strict availability requirements. The lack of known exploits reduces immediate risk, but organizations should consider the vulnerability a significant threat due to the potential impact on system stability and security. Disruption of VPN services could also affect compliance with data protection regulations such as GDPR if secure communications are interrupted.

Monitor OpenVPN vendor communications closely for official patches or updates addressing CVE-2025-50054 and apply them promptly once available. Implement strict access controls and endpoint security measures to limit local user access to systems running vulnerable OpenVPN versions, reducing the risk of exploitation by unauthorized users. Use application whitelisting and endpoint detection and response (EDR) solutions to detect and prevent suspicious local processes attempting to interact with the ovpn-dco-win driver. Temporarily disable or restrict the use of the ovpn-dco-win kernel driver component if feasible, or revert to OpenVPN versions that do not include the vulnerable DCO feature until patches are released. Conduct regular system and security audits to identify and remediate unauthorized local access or privilege escalation attempts. Educate users and administrators about the risks of running untrusted local code and the importance of maintaining updated VPN client software. Implement network segmentation to isolate critical systems and VPN endpoints, limiting the impact of potential local exploits. Leverage Windows security features such as Kernel Patch Protection (PatchGuard) and Driver Signature Enforcement to reduce the risk of kernel-level exploits.