CVE-2025-21359 Overview
CVE-2025-21359 is a Windows Kernel security feature bypass vulnerability affecting a broad range of Microsoft Windows client and server operating systems. The flaw allows an authenticated local attacker to bypass kernel-enforced security boundaries, potentially compromising confidentiality, integrity, and availability of the host. Microsoft published guidance for this issue through the Microsoft Security Response Center (MSRC) advisory. The vulnerability is classified under CWE-284: Improper Access Control.
Critical Impact
A local, low-privileged attacker can bypass Windows Kernel security controls to gain elevated access, undermining process isolation and protection mechanisms relied upon by the operating system.
Affected Products
- Microsoft Windows 10 (1507, 1607, 1809, 21H2, 22H2) and Windows 11 (22H2, 23H2, 24H2)
- Microsoft Windows Server 2008, 2008 R2, 2012, 2012 R2, 2016, 2019, 2022, 2022 23H2
- Microsoft Windows Server 2025
Discovery Timeline
- 2025-02-11 - CVE-2025-21359 published to NVD
- 2025-02-28 - Last updated in NVD database
Technical Details for CVE-2025-21359
Vulnerability Analysis
The vulnerability resides in the Windows Kernel and stems from improper access control enforcement. An authenticated attacker with low privileges on the target system can interact with kernel-exposed interfaces in a manner that circumvents intended security checks. Successful exploitation leads to a bypass of kernel-level protections that ordinarily separate user-mode code from privileged operations.
The issue does not require user interaction and operates within a single security scope on the local machine. Because the kernel mediates access to nearly all system resources, a bypass at this layer can be chained with other vulnerabilities to achieve privilege escalation, defense evasion, or persistent compromise.
Root Cause
The root cause is mapped to [CWE-284 (Improper Access Control)]. The kernel fails to consistently enforce a security boundary, allowing operations that should be restricted to higher-privileged callers. Microsoft has not published the specific component or function affected in public NVD data; refer to the Microsoft Security Update CVE-2025-21359 advisory for vendor-specific technical context.
Attack Vector
Exploitation requires local access and valid credentials on the target host. An attacker first establishes a foothold through phishing, credential theft, or another initial-access technique. The attacker then runs code that invokes the vulnerable kernel path to bypass the security feature. Remote exploitation is not possible without prior local access.
No public proof-of-concept exploit is currently available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Detailed exploitation primitives have not been disclosed in public references.
Detection Methods for CVE-2025-21359
Indicators of Compromise
- Unexpected loading of unsigned or suspicious kernel-mode drivers on patched-but-unrebooted hosts.
- Execution of unfamiliar binaries from temporary or user-writable directories that subsequently spawn elevated child processes.
- Anomalous token manipulation events or process integrity-level changes following local user logons.
Detection Strategies
- Monitor Windows Security and Sysmon event logs for abnormal process creation chains originating from standard user contexts that lead to SYSTEM-level operations.
- Correlate local logon events with subsequent kernel object access failures and driver-load events to surface bypass attempts.
- Apply behavioral analytics to flag low-privileged processes performing operations typically reserved for privileged callers.
Monitoring Recommendations
- Ensure Microsoft Defender, EDR agents, and kernel-event collection are deployed across all Windows endpoints and servers in scope.
- Centralize endpoint telemetry into a SIEM or data lake to enable cross-host correlation of privilege-escalation patterns.
- Track patch deployment status using configuration management tooling and alert on hosts that remain unpatched beyond your remediation SLA.
How to Mitigate CVE-2025-21359
Immediate Actions Required
- Apply the February 2025 Microsoft security updates referenced in the MSRC advisory for CVE-2025-21359 to all affected Windows client and server versions.
- Prioritize patching on multi-user systems, jump hosts, and servers where local accounts are present.
- Audit local account usage and remove unnecessary interactive logon rights for non-administrative users.
Patch Information
Microsoft addressed CVE-2025-21359 in the security updates published on the MSRC advisory page. Administrators should consult the advisory for the specific KB article and build numbers that apply to each supported Windows version, then deploy through Windows Update, WSUS, Microsoft Intune, or equivalent patch management tooling.
Workarounds
- Restrict local logon rights and enforce least-privilege policies to reduce the pool of accounts able to trigger the vulnerability.
- Enable attack surface reduction rules and credential guard features to limit post-exploitation movement.
- Segment administrative workstations from general-purpose endpoints to contain potential compromise.
# Verify installed updates on a Windows host
Get-HotFix | Sort-Object -Property InstalledOn -Descending | Select-Object -First 20
# Check current Windows build to validate patch level
[System.Environment]::OSVersion.Version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.