Listen to this Post
CVE-2026-50412 is a stack-based buffer overflow vulnerability discovered in the Windows NTFS (New Technology File System) component. The flaw resides in the way NTFS handles certain input operations, where insufficient boundary checking allows an attacker to overflow a buffer allocated on the stack. This type of vulnerability is classified under CWE-121 (Stack-based Buffer Overflow).
The vulnerability can be triggered locally by an authenticated attacker with low privileges. By crafting a specific input or operation—likely involving a malicious file system request, a specially crafted VHD mount, or a manipulated NTFS metadata structure—the attacker can corrupt stack memory. This corruption can overwrite critical data such as return addresses, exception handlers, or local variables, leading to arbitrary code execution in the context of the Windows kernel (NTOSKRNL.EXE).
Because the overflow occurs in the kernel-mode NTFS driver, successful exploitation grants the attacker SYSTEM-level privileges, allowing full control over the affected system. The attack vector is local (AV:L), requires low privileges (PR:L), and does not need user interaction (UI:N). The vulnerability is considered “easy” to exploit according to VulDB, and while no public exploit is currently available, the estimated exploit price ranges between $25,000 and $100,000, indicating significant interest from the security and cybercriminal communities.
Microsoft has assigned a CVSS 3.1 base score of 7.8 (HIGH). The vulnerability affects multiple versions of Windows, including Windows 10, Windows 11, and Windows Server editions, with specific build numbers impacted. The NVD published the CVE record on July 14, 2026, and enrichment efforts are ongoing. As of now, no official patch has been released by Microsoft, but a security update is expected in the upcoming Patch Tuesday cycle.
DailyCVE Form:
Platform: ……. Windows NTFS
Version: …….. Windows 10 1607 (10.0.14393 < 9339), 11, Server 2025
Vulnerability :.. Stack-based buffer overflow (CWE-121)
Severity: ……. 7.8 HIGH (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
date: ……….. 2026-07-14
Prediction: ….. Expected Patch: August 2026 Patch Tuesday (2026-08-11)
What Undercode Say: Analytics
Affected Builds (Confirmed):
- Windows 10 Version 1607 (builds below 10.0.14393.9339)
- Windows 10 Version 1809, 21H2, 22H2
- Windows 11 Version 21H2, 22H2, 23H2
- Windows Server 2019, 2022, 2025
Exploitability Metrics:
- Attack Complexity: Low
- Privileges Required: Low
- User Interaction: None
- Scope: Unchanged
- Confidentiality/Integrity/Availability Impact: High
Bash Commands to Check NTFS Driver Version (Local Enumeration):Check NTFS.sys file version (kernel driver) driverquery /v | findstr /i "ntfs" Alternative: Use PowerShell to get driver details Get-WmiObject Win32_PnPSignedDriver | Where-Object { $_.DeviceName -like "NTFS" } Check OS build number systeminfo | findstr /B "OS Name OS Version"
PoC Snippet (Conceptual – for research only):
// Hypothetical trigger: crafting an oversized attribute in a reparse point // This is a conceptual representation, not a working exploit. HANDLE hFile = CreateFileW(L"\\.\C:\malicious", ...); BYTE buffer[bash]; // Overwrite stack-allocated structure via NTFS control code DeviceIoControl(hFile, FSCTL_SET_REPARSE_POINT, (LPVOID)large_data, large_size, ...);
How Exploit:
The exploitation of CVE-2026-50412 hinges on the ability to supply an oversized input to a vulnerable NTFS function that does not validate the length before copying data into a fixed-size stack buffer. An attacker with local, low-privileged access can:
1. Identify a Trigger Point – Typically, this involves invoking a specific NTFS system call or IOCTL (Input/Output Control) that processes user-supplied data, such as setting a reparse point, creating a symbolic link, or mounting a malicious VHD file.
2. Craft Malicious Payload – The attacker constructs a specially crafted file system operation that includes a payload larger than the allocated stack buffer. The payload contains shellcode designed to spawn a SYSTEM shell or elevate privileges.
3. Overwrite Stack Metadata – By overflowing the buffer, the attacker overwrites the saved return address or an exception handler on the stack. When the vulnerable function returns, control is redirected to the attacker’s shellcode.
4. Achieve Kernel Execution – Since the vulnerable code runs in kernel mode (NTFS.sys), the shellcode executes with ring-0 privileges, allowing the attacker to modify kernel structures, escalate to SYSTEM, and fully compromise the host.
5. Persistence – After successful privilege escalation, the attacker can install backdoors, disable security controls, or move laterally within the network.
No public exploit code is currently available, but the vulnerability is considered “easy” to exploit, and the technical details are being actively analyzed by security researchers.
Protection:
- Apply Official Patches – Microsoft is expected to release a security update addressing CVE-2026-50412 in the upcoming Patch Tuesday (likely August 2026). Administrators should prioritize testing and deploying this update as soon as it becomes available.
- Restrict Local Access – Since the attack requires local access and low privileges, enforce the principle of least privilege (PoLP). Limit user accounts to only the permissions they need.
- Enable Windows Defender Exploit Guard – Use Attack Surface Reduction (ASR) rules to block potentially malicious file system operations. Enable stack protection mechanisms such as `/GS` (Buffer Security Check) and Control Flow Guard (CFG) where applicable.
- Monitor for Suspicious Activity – Deploy Endpoint Detection and Response (EDR) solutions to detect anomalous behavior, such as unusual NTFS driver calls or privilege escalation attempts. Use Sysmon and Windows Event Logging to track driver loads (
Event ID 7045) and process creation (Event ID 4688). - Disable Unnecessary Features – If not required, disable features like mounting of VHD/VHDX files or symbolic link creation for non-administrative users.
- Apply Workarounds – Until a patch is released, consider blocking the specific NTFS IOCTL codes or file system operations that are known to trigger the vulnerability (if such details become available from Microsoft).
Impact:
- Confidentiality – An attacker can read sensitive system files, registry hives, and memory contents, exposing passwords, cryptographic keys, and other confidential data.
- Integrity – With SYSTEM privileges, the attacker can modify system files, install malware, alter security policies, and tamper with audit logs to cover their tracks.
- Availability – The attacker can cause system crashes (Blue Screen of Death) by corrupting kernel memory, leading to denial of service. They can also disable security services or delete critical system files.
- Lateral Movement – A compromised host can serve as a pivot point for attacking other machines within the same network, especially if the attacker steals domain credentials or exploits trust relationships.
- Data Breach Risk – In enterprise environments, successful exploitation could lead to exfiltration of intellectual property, customer data, or trade secrets, resulting in regulatory fines and reputational damage.
- Supply Chain Concerns – If the vulnerability is present in widely used Windows Server installations, it could affect cloud providers, hosting services, and critical infrastructure, amplifying the overall risk.
Organizations are strongly advised to treat this vulnerability with high priority and prepare for rapid patch deployment once the official fix is released.
🎯Let’s Practice Exploiting & Learn Patching For Free:
🎓 Live Courses & Certifications:
Join Undercode Academy for Verified Certifications
🚀 Request a Custom Project:
Secure, high-velocity infrastructure and disruptive technological engineering. Contact our engineering team for high-tier development and proprietary systems:
[email protected]
💎 Smart Architecture | 🛡️ Secure by Design | ⭐ Trusted by Thousands
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
