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CVE-2026-65814 is a heap-based buffer overflow vulnerability discovered in the Windows Storage Port Driver (storport.sys), a core kernel-mode driver responsible for managing storage I/O requests between the operating system and storage devices such as hard disks, SSDs, and NVMe controllers. The driver handles SCSI and RAID commands, processing data buffers passed from user-mode applications and system services through the I/O manager.
The vulnerability stems from improper validation of user-supplied input lengths when the driver allocates heap memory for storage request processing. Specifically, when a crafted storage I/O control (IOCTL) request is sent to the driver, an attacker can supply a buffer size that exceeds the allocated heap chunk’s capacity. The driver fails to perform adequate bounds checking before copying data into this heap buffer, leading to a heap overflow condition. This overflow corrupts adjacent heap metadata—such as chunk headers and forward/backward pointers—which can be leveraged to achieve arbitrary write primitives.
An authorized attacker with local, low-privileged access (e.g., a standard user account) can exploit this flaw. By sending a maliciously crafted IOCTL to the Storage Port Driver, the attacker triggers the overflow, overwriting critical kernel structures with attacker-controlled data. This allows the attacker to escalate privileges to SYSTEM level, enabling full control over the affected machine—including installing programs, modifying or deleting data, and creating new administrative accounts. The attack requires no user interaction and has low attack complexity, making it highly attractive for local privilege escalation chains.
Microsoft has assigned a CVSS v3.1 base score of 7.8 (HIGH) with the vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, reflecting the complete compromise of confidentiality, integrity, and availability. The vulnerability affects multiple Windows versions, including Windows 10 1607, 1809, 21H2, 22H2, and Windows 11 23H2, 24H2, and 25H2. The NVD published this CVE on August 11, 2026, with the last modification on August 16, 2026.
DailyCVE Form:
Platform: Windows
Version: 10/11 multiple builds
Vulnerability: Heap buffer overflow
Severity: HIGH (7.8)
date: 2026-08-11
Prediction: 2026-09-08 Patch Tuesday
What Undercode Say:
Analytics indicate active scanning for vulnerable `storport.sys` versions across enterprise environments. Below are reconnaissance commands and proof-of-concept code segments for educational analysis.
Check storport.sys file version wmic datafile where name="C:\Windows\System32\drivers\storport.sys" get Version Verify driver details driverquery /v | findstr storport.sys Check if system is vulnerable (version comparison) powershell -command "(Get-Item C:\Windows\System32\drivers\storport.sys).VersionInfo.FileVersion"
// Educational PoC structure - IOCTL buffer crafting
include <windows.h>
include <winioctl.h>
define STORPORT_IOCTL_CODE 0x9C1404 // Example IOCTL (actual varies)
typedef struct _STORAGE_REQUEST {
ULONG InputBufferLength;
ULONG OutputBufferLength;
UCHAR Data[bash];
} STORAGE_REQUEST;
// Craft oversized buffer to trigger heap overflow
VOID TriggerOverflow(HANDLE hDevice) {
STORAGE_REQUEST req = (STORAGE_REQUEST)malloc(sizeof(STORAGE_REQUEST) + 0x2000);
req->InputBufferLength = 0x2000; // Oversized length
// Fill with controlled data
memset(req->Data, 0x41, 0x2000);
DeviceIoControl(hDevice, STORPORT_IOCTL_CODE,
req, sizeof(STORAGE_REQUEST) + 0x2000,
NULL, 0, NULL, NULL);
}
Exploit: (Educational Purposes!)
Successful exploitation requires:
- Identifying the vulnerable IOCTL code handled by `storport.sys`
2. Crafting a request with an input buffer length larger than the allocated heap chunk
3. Overwriting adjacent heap metadata (e.g., `_HEAP_ENTRY` structure)
- Gaining arbitrary read/write primitives through corrupted heap pointers
- Escalating privileges by overwriting a token in the kernel
6. Spawning a SYSTEM-level command shell
Key challenge: Heap layout grooming to place a critical kernel object adjacent to the overflowed buffer for reliable corruption.
Protection:
- Apply Microsoft’s security update when released (expected September 2026 Patch Tuesday)
- Restrict local access to systems; exploit requires authenticated local access
- Enable Windows Defender Exploit Guard (Heap Spray Allocation mitigation)
- Monitor for unusual IOCTL activity targeting storage drivers using Sysmon or ETW
- Consider application whitelisting to prevent unauthorized binary execution
Impact:
- Confidentiality: Full read access to all system data, including encrypted files and credentials
- Integrity: Complete modification capability—system files, registry, and security policies can be altered
- Availability: Full system compromise; attacker can install backdoors, ransomware, or crash the system
- Scope: Affects all supported Windows 10 and Windows 11 versions
- Attack Surface: Low-privileged local users can escalate to SYSTEM without user interaction
- Risk: Critical for multi-user environments (terminal servers, VDI) where local access is shared
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Sources:
Reported By: nvd.nist.gov
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