CVE-2026-85377 in Windows
Summary
by MITRE • 10/14/2026
Access of resource using incompatible type ('type confusion') in Windows CD-ROM Driver allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability described involves a critical flaw within the Microsoft Windows CD-ROM driver, specifically categorized as a type confusion error that leads to unauthorized privilege escalation. This issue arises when the operating system's kernel-mode components handle requests from user-space applications interacting with optical drive hardware. In this specific scenario, an attacker who has already gained local access on the target machine can exploit improper handling of data types passed between different layers of the driver stack. The core technical flaw lies in the failure to validate or correctly cast input parameters before they are processed by sensitive kernel routines. When a malicious actor supplies specially crafted IOCTL (Input/Output Control) requests, the CD-ROM driver misinterprets the memory layout or structure of these inputs due to incompatible type assumptions. This mismatch allows the attacker to manipulate internal pointers or control flow mechanisms within the kernel space, effectively bypassing standard security boundaries that separate user-mode applications from privileged system operations.
From a technical perspective, this vulnerability aligns with CWE-843, which defines access using an incorrect type where the object is accessed via an incompatible data structure or pointer. The exploitation of such flaws typically involves crafting specific memory structures that trick the driver into executing code paths intended for different types of objects. By leveraging this inconsistency, a local attacker can achieve arbitrary read/write capabilities within kernel memory. This capability is particularly dangerous because it allows the modification of critical system structures, such as access control lists or token manipulation routines. Consequently, an unprivileged user process can escalate its privileges to that of SYSTEM, gaining full administrative control over the compromised host. The severity of this issue is compounded by the fact that CD-ROM drivers are fundamental components present in most Windows installations, making them a persistent attack surface for local privilege escalation attempts.
The operational impact of successfully exploiting this vulnerability is severe, as it results in complete compromise of the affected system's integrity and confidentiality. An attacker with low-level access can install rootkits, disable security software, exfiltrate sensitive data, or use the compromised machine as a pivot point to attack other systems within the network. This aligns with MITRE ATT&CK technique T1068, which covers exploitation for privilege escalation, specifically through techniques that target kernel vulnerabilities. The ability to elevate privileges locally is often a prerequisite for more advanced persistent threat activities, including lateral movement and data staging. Because this vulnerability exists in a core system driver, it affects a wide range of Windows versions unless specific mitigations are applied. Organizations must recognize that even seemingly minor hardware drivers can serve as vectors for significant security breaches if they contain logic errors related to type safety and memory management.
Mitigation strategies primarily focus on applying the latest security patches released by Microsoft, which address the underlying code defects in the CD-ROM driver's input validation routines. Administrators should ensure that all systems are updated with the most recent cumulative updates to close this specific gap. In environments where patching is not immediately feasible, restricting local user privileges can reduce the attack surface significantly. Implementing strict application whitelisting and disabling unnecessary services or drivers may also help mitigate the risk of exploitation. Furthermore, deploying endpoint detection and response solutions that monitor for anomalous kernel-mode activity can provide an additional layer of defense by detecting attempts to exploit type confusion vulnerabilities in real time. Regular security audits and adherence to secure coding standards during driver development are essential preventive measures against such logic errors in future software releases.