CVE-2026-69535 in Windows
Summary
by MITRE • 09/09/2026
Numeric truncation error in Windows Spaceport.sys allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified within the Windows Spaceport.sys driver represents a critical security flaw stemming from improper handling of numeric data during input validation processes. Specifically, this issue is classified as a Numeric Truncation Error, which aligns with Common Weakness Enumeration identifier CWE-197. This type of defect occurs when an application performs arithmetic operations or assigns values to variables without ensuring that the resulting value fits within the allocated storage space for its data type. In the context of Spaceport.sys, this likely involves a scenario where a larger integer value is cast into a smaller integer variable, such as converting a 32-bit unsigned long to an 8-bit char or similar narrow type. This truncation causes the high-order bits containing critical magnitude information to be discarded, resulting in a significantly smaller numerical value than originally intended by the system logic.
From a technical perspective, this flaw typically manifests during boundary checks or array indexing operations within the driver's kernel-mode execution context. When an attacker provides crafted input that triggers this truncation, the validation logic may incorrectly determine that a requested operation is safe because it perceives the truncated value as being within acceptable bounds. For instance, if the code intends to verify that an index does not exceed a buffer size of one thousand elements but receives a large number like ten thousand and five hundred, casting this to a smaller type might result in a small positive integer such as fifty-five due to overflow behavior. The driver then proceeds to access memory at offset fifty-five instead of rejecting the out-of-bounds request, thereby bypassing essential security controls designed to prevent buffer overflows or unauthorized memory accesses.
The operational impact of this vulnerability is severe because it facilitates Local Privilege Escalation on affected Microsoft Windows systems. Since Spaceport.sys operates with high privileges in kernel mode, exploiting this flaw allows an authenticated local attacker to execute arbitrary code within the context of the operating system's most privileged account. This effectively grants the attacker full control over the compromised machine, enabling them to install programs, view, change, or delete critical data, and create new accounts with complete user rights. The ability to escalate privileges from a standard user level to SYSTEM-level access undermines the fundamental security model of the Windows operating system, which relies on strict privilege separation to contain potential breaches.
This vulnerability is closely associated with MITRE ATT&CK technique T1068, specifically the sub-technique for Exploitation for Privilege Escalation. Attackers leveraging this flaw would typically follow a post-exploitation workflow where they first gain initial access through phishing or other entry vectors and then utilize this driver vulnerability to elevate their session privileges before proceeding with lateral movement or data exfiltration. The presence of such vulnerabilities in core system drivers highlights the risks associated with complex kernel codebases that handle hardware interactions and user-mode requests, as errors here have systemic consequences rather than affecting only isolated applications.
Mitigation strategies for this issue primarily involve applying the security updates provided by Microsoft to patch the underlying flaw in Spaceport.sys. Organizations should ensure that all endpoints are updated with the latest cumulative patches released by Microsoft to address known driver vulnerabilities. Additionally, implementing strict application control policies can help prevent unauthorized drivers from loading or interacting with system components if such a vulnerability were exploited before a patch is available. Security teams should also monitor for anomalous behavior indicative of privilege escalation attempts, such as unexpected changes in token privileges or unusual kernel-mode activity, using endpoint detection and response solutions to identify potential exploitation activities in real time.