CVE-2026-62700 Overview
CVE-2026-62700 is a heap-based buffer overflow vulnerability in the Windows New Technology File System (NTFS) driver. An authenticated local attacker can trigger the flaw to corrupt kernel heap memory and elevate privileges on affected systems. The vulnerability affects a broad range of supported Windows client and server releases, including Windows 10, Windows 11, and Windows Server versions from 2012 through 2025. Microsoft has assigned the flaw a CVSS 3.1 base score of 7.8 and categorized it under CWE-122: Heap-based Buffer Overflow.
Critical Impact
Successful exploitation allows a low-privileged local user to gain SYSTEM-level privileges, resulting in full compromise of confidentiality, integrity, and availability on the affected host.
Affected Products
- Microsoft Windows 10 (1607, 1809, 21H2, 22H2) across x86, x64, and ARM64 architectures
- Microsoft Windows 11 (23H2, 24H2, 25H2, 26H1) across x64 and ARM64 architectures
- Microsoft Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025
Discovery Timeline
- 2026-08-11 - CVE-2026-62700 published to NVD
- 2026-08-13 - Last updated in NVD database
Technical Details for CVE-2026-62700
Vulnerability Analysis
The vulnerability resides in the NTFS driver, the kernel-mode component responsible for parsing and managing NTFS-formatted volumes. A heap-based buffer overflow occurs when the driver writes data beyond the boundaries of an allocated heap buffer during file system operations. Because NTFS runs in kernel context, memory corruption in this component directly translates into kernel-level compromise.
An authorized attacker with local access and low privileges can craft input that triggers the overflow. Microsoft's advisory categorizes the flaw as a local elevation of privilege issue with no user interaction requirement beyond the attacker's own actions. The EPSS model currently estimates a low near-term exploitation probability, but heap overflows in NTFS have historically been weaponized in post-compromise chains.
Root Cause
The root cause is improper bounds validation during heap buffer operations within NTFS, classified under CWE-122. The driver allocates a heap buffer of insufficient size relative to attacker-controlled input, then writes past the allocation. Adjacent kernel pool structures become corruptible, enabling manipulation of kernel objects to hijack control flow or escalate token privileges.
Attack Vector
Exploitation requires local access and a valid low-privileged account on the target system. The attacker interacts with NTFS through standard file system operations, such as mounting a crafted volume, opening or manipulating specially constructed files, or invoking file system control codes that reach the vulnerable code path. No network access and no user interaction from another principal are required. Refer to the Microsoft Security Update for detailed exploitation prerequisites.
Detection Methods for CVE-2026-62700
Indicators of Compromise
- Unexpected kernel-mode crashes or bug checks referencing ntfs.sys, particularly PAGE_FAULT_IN_NONPAGED_AREA or pool corruption stops
- Creation of new processes running as NT AUTHORITY\SYSTEM from parent processes owned by standard users shortly after file system activity
- Mounting of unusual VHD, VHDX, or ISO images by non-administrative users prior to privilege changes
Detection Strategies
- Monitor Windows Event Log IDs 1001 (BugCheck) and 41 (Kernel-Power) for kernel faults implicating the NTFS driver
- Correlate file system driver crashes with subsequent process token elevation on the same host
- Baseline and alert on unusual FSCTL and IOCTL invocations against NTFS volumes by non-administrative processes
Monitoring Recommendations
- Enable Windows Defender Application Control and Attack Surface Reduction rules that restrict untrusted image mounting
- Ingest Sysmon Event ID 1 (process create) and Event ID 11 (file create) into a centralized SIEM to correlate NTFS activity with elevation events
- Track patch status for the NTFS driver across the fleet and alert on hosts running unpatched builds
How to Mitigate CVE-2026-62700
Immediate Actions Required
- Apply the security update referenced in the Microsoft Security Update Guide for CVE-2026-62700 to all affected Windows client and server builds
- Prioritize patch deployment on multi-user systems, terminal servers, and jump hosts where local low-privileged accounts exist
- Audit local account inventory and remove unnecessary interactive logon rights on servers
Patch Information
Microsoft has released cumulative security updates addressing CVE-2026-62700 for all supported Windows 10, Windows 11, and Windows Server versions listed in the affected products section. Administrators should deploy the corresponding monthly rollup or standalone security update via Windows Update, Windows Server Update Services (WSUS), or Microsoft Update Catalog. Consult the Microsoft Security Update advisory for the KB article numbers mapped to each build.
Workarounds
- Restrict the ability of standard users to mount arbitrary disk images (VHD, VHDX, ISO) using Group Policy or AppLocker until patches are applied
- Enforce least privilege and remove local administrative rights from end-user accounts to limit lateral impact of an elevation event
- Enable Hypervisor-Protected Code Integrity (HVCI) and Virtualization-Based Security (VBS) to raise the difficulty of kernel exploitation
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
