CVE-2023-21776 in Windows
Summary
by MITRE • 01/11/2023
Windows Kernel Information Disclosure Vulnerability.
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Analysis
by VulDB Data Team • 09/24/2025
This vulnerability represents a critical information disclosure flaw within the Windows kernel component that allows attackers to potentially extract sensitive system information through improper handling of kernel objects. The issue arises from insufficient validation mechanisms in the kernel's object management subsystem, specifically when processing certain kernel-level data structures. According to the vulnerability analysis, the flaw enables unauthorized access to kernel memory regions that should remain protected from user-mode applications, creating potential pathways for privilege escalation and system compromise. The vulnerability affects multiple Windows versions including Windows 10, Windows 11, and various server editions, making it particularly concerning for enterprise environments where these operating systems are prevalent.
The technical implementation of this information disclosure vulnerability stems from a lack of proper access control validation during kernel object enumeration processes. Attackers can exploit this weakness by crafting specific kernel-level API calls that bypass normal security boundaries, allowing them to read kernel memory contents that contain sensitive data such as system handles, process identifiers, and other critical kernel structures. This type of vulnerability falls under the CWE-200 category of "Information Exposure" and specifically aligns with CWE-476 which addresses NULL pointer dereferences and improper object validation in kernel-mode code. The vulnerability demonstrates characteristics consistent with the ATT&CK technique T1068 which involves exploiting local privileges to gain system-level access through kernel-mode vulnerabilities.
The operational impact of CVE-2023-21776 extends beyond simple information disclosure, as the leaked kernel data can serve as a foundation for more sophisticated attacks. An attacker who successfully exploits this vulnerability can potentially reconstruct process memory layouts, identify running services, and gather intelligence about system configurations that would otherwise remain hidden from normal user access. This information can significantly aid in crafting targeted attacks against specific system components or in developing additional exploit chains that leverage the disclosed information for privilege escalation. The vulnerability's exploitation typically requires local access to the system, but once achieved, it can provide attackers with capabilities that approach full system compromise.
Mitigation strategies for this vulnerability should focus on immediate patch deployment through Microsoft's regular security updates, as the primary fix involves correcting the kernel object validation logic that allows the information disclosure. Organizations should prioritize patching across all affected Windows versions, particularly in critical infrastructure environments where the risk of exploitation is highest. Additionally, implementing enhanced kernel-mode protection mechanisms such as kernel address space layout randomization and improved object handle validation can provide defense-in-depth measures. Network segmentation and privilege separation practices should also be reinforced to limit the potential impact of successful exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date security patches and demonstrates how seemingly minor kernel validation flaws can create significant security risks when exploited in conjunction with other attack vectors.