CVE-2026-88091 in Windows
Summary
by MITRE • 10/14/2026
Deserialization of untrusted data in Windows Management Instrumentation allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
Windows Management Instrumentation (WMI) serves as a core infrastructure component within the Microsoft Windows operating system, providing a standardized interface for accessing management information and operations related to the operating system, devices, applications, and services. The vulnerability described involves a critical flaw in how WMI processes serialized data objects received from external or untrusted sources. Specifically, the issue stems from improper validation of input during the deserialization process, where the application fails to adequately verify that the incoming data structure matches expected formats or types before processing it. This lack of rigorous type checking and boundary verification allows an attacker who has already gained authorized access to a system to craft maliciously formatted serialized objects that exploit this logic error.
When such untrusted data is deserialized, the flawed parsing routine may execute unintended code paths or manipulate internal memory structures in ways not anticipated by the developers. This typically leads to arbitrary code execution within the security context of the WMI service process. Since WMI services often run with high-level privileges, including SYSTEM level access on many configurations, successfully exploiting this vulnerability enables a local attacker to escalate their privileges from standard user rights to those of an administrator or system account. The core technical flaw aligns closely with CWE-502, which denotes Deserialization of Untrusted Data, as the root cause is the trust placed in data structures without sufficient integrity verification prior to instantiation and execution.
The operational impact of this vulnerability is severe due to its potential for local privilege escalation. An attacker who has obtained valid credentials on a target machine can leverage this flaw to bypass standard security controls that restrict user actions. Once elevated privileges are achieved, the attacker gains full control over the compromised system. This includes the ability to install programs, view, change, or delete confidential data, and create new accounts with unrestricted permissions. The exploitation does not require physical access but relies on network-based authentication or local login capabilities, making it a significant threat in environments where user credentials may be compromised through phishing, credential stuffing, or other initial access vectors.
From an offensive security perspective, this vulnerability is categorized under the MITRE ATT&CK framework technique T1068, which covers Exploitation for Privilege Escalation. Attackers typically utilize this method after gaining a foothold on the network to move laterally and establish persistence with higher-level access. The exploitation often involves crafting specific WMI queries or event subscriptions that trigger the vulnerable deserialization routine within the svchost.exe process hosting the WMI service. Because WMI is deeply integrated into Windows, detecting such activity can be challenging without specialized monitoring tools that inspect memory states and object instantiation patterns for anomalies indicative of malicious serialization payloads.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. The primary defense is to apply vendor-provided security updates or patches as soon as they become available, which typically involve hardening the deserialization logic to enforce strict type checking and input validation. Organizations should also implement least privilege principles by restricting WMI access permissions for standard users where possible, although this can be complex due to system dependencies. Additionally, deploying endpoint detection and response solutions that monitor for unusual process creation or memory injection patterns associated with WMI exploitation can help identify attempts in real-time. Regular auditing of user accounts and enforcement of strong authentication mechanisms further reduces the risk of initial unauthorized access that precedes such privilege escalation attacks.