CVE-2026-69595 in Windows
Summary
by MITRE • 09/08/2026
Use after free in Windows Services for NFS ONCRPC XDR Driver allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 09/08/2026
The vulnerability described involves a critical use-after-free flaw within the Windows Services for Network File System, specifically affecting the ONC/RPC XDR driver component. This security defect arises from improper memory management practices where the system continues to reference a block of memory after it has been freed or deallocated by another part of the operating system. In the context of network-facing services like NFS, this flaw is particularly severe because it can be triggered remotely without requiring any form of user interaction or local authentication on the target machine. An attacker positioned within reach of the vulnerable service can craft a specially designed packet that exploits this memory corruption state to gain unauthorized access and execute arbitrary code with elevated privileges, effectively compromising the integrity and confidentiality of the affected system.
From a technical perspective, the ONC/RPC XDR driver is responsible for handling data serialization and deserialization in remote procedure calls used by NFS implementations. When processing malformed or maliciously crafted input packets, the driver fails to properly validate pointers before dereferencing them after they have been released back to the memory pool. This race condition or logic error allows an attacker to control the content of that freed memory region through heap spraying techniques or other exploitation methods. By overwriting the freed memory with controlled data structures, the attacker can manipulate function pointers or return addresses within the kernel context. Consequently, when the system attempts to use this corrupted pointer, it redirects execution flow to the attacker-controlled code, leading to arbitrary code execution in the highest privilege level available on the operating system.
The operational impact of this vulnerability is profound, as successful exploitation grants an attacker full control over the affected Windows host. This includes the ability to install programs, view, change, or delete data, and create new accounts with full user rights. Since the flaw exists within a network service component, it significantly expands the attack surface beyond local boundaries. Attackers can leverage this vulnerability for lateral movement across enterprise networks, persistence through backdoor installation, or as an initial entry point in broader intrusion campaigns. The lack of authentication requirements means that any host on the same network segment with NFS services enabled is potentially at risk, making rapid patching and configuration hardening essential to prevent widespread compromise.
This issue aligns closely with Common Weakness Enumeration identifier CWE-416, which defines use-after-free errors as a class of memory safety vulnerabilities where software continues to use a pointer after it has been freed. In terms of the MITRE ATT&CK framework, this vulnerability facilitates techniques associated with initial access and privilege escalation, specifically leveraging remote code execution capabilities inherent in buffer overflow or memory corruption flaws. Defense strategies must prioritize immediate application of vendor-supplied security patches that address the underlying memory management logic within the ONC/RPC XDR driver. Additionally, organizations should consider disabling NFS services if they are not strictly required for business operations to reduce the attack surface. Network segmentation and strict firewall rules limiting access to port 111 (RPC) and associated NFS ports can also provide a layer of defense against exploitation attempts from untrusted networks or external threats.