CVE-2023-20511: AMD Kernel Driver Use-After-Free Vulnerability

CVE-2023-20511 Overview

CVE-2023-20511 is a double free vulnerability in the AMD kernel mode driver (KMD). The flaw stems from the release of an invalid pointer within the driver. A privileged attacker can trigger a double free condition, potentially leading to arbitrary code execution in kernel context. The weakness is classified under [CWE-763] Release of Invalid Pointer or Reference. AMD documented the issue in security bulletin AMD-SB-6018. Exploitation requires high privileges, user interaction, and high attack complexity, which limits opportunistic abuse but does not eliminate risk in multi-tenant or hardened environments.

Critical Impact
Successful exploitation can result in arbitrary code execution within the Windows kernel, granting an attacker full control of the affected host.

Affected Products

AMD Kernel Mode Driver (KMD)
AMD graphics driver components referenced in bulletin AMD-SB-6018
Windows systems running vulnerable AMD driver versions

Discovery Timeline

2026-08-31 - CVE-2023-20511 published to NVD
2026-09-03 - Last updated in NVD database

Technical Details for CVE-2023-20511

Vulnerability Analysis

The vulnerability resides in the AMD kernel mode driver, which handles graphics operations and hardware interaction at ring 0. The driver releases a pointer that is invalid or already freed, producing a double free condition. Double free bugs corrupt the kernel heap allocator's internal state by returning the same memory region to the free list twice.

An attacker who controls subsequent allocations can influence which object is placed at the reclaimed address. Manipulating the freed slot enables kernel memory corruption and, ultimately, arbitrary code execution in kernel context. Exploitation requires an authenticated local process with existing high privileges and user interaction, reflecting the constrained trigger path documented by AMD.

Root Cause

The root cause is improper pointer lifetime management in the AMD KMD. The driver fails to invalidate or track ownership of a pointer after it is freed, then releases the same reference a second time. This maps to [CWE-763] Release of Invalid Pointer or Reference and is a common source of kernel heap corruption when driver IOCTL handlers do not enforce single-owner semantics on allocated objects.

Attack Vector

A local attacker with high privileges invokes the vulnerable code path through the AMD driver interface, typically via a crafted IOCTL sequence. The attacker triggers the code path that releases the invalid pointer twice, then races or grooms the kernel pool to place attacker-controlled data into the reclaimed allocation. Because no verified public proof-of-concept is available, refer to the AMD Security Bulletin AMD-SB-6018 for technical details on affected driver interfaces.

Detection Methods for CVE-2023-20511

Indicators of Compromise

Unexpected kernel bugchecks (BSOD) referencing AMD driver modules such as amdkmdag.sys or related KMD components
Crash dumps showing DOUBLE_FREE, pool corruption, or invalid pointer dereference within AMD driver frames
Unsigned or unexpected processes issuing DeviceIoControl calls to AMD display device objects

Detection Strategies

Monitor Windows Error Reporting and kernel crash telemetry for repeated faults originating in AMD KMD modules
Baseline legitimate AMD driver IOCTL callers and alert on non-graphics processes interacting with AMD device handles
Correlate driver crashes with subsequent process privilege changes or persistence artifacts

Monitoring Recommendations

Enable Driver Verifier with pool tracking and special pool for AMD KMD in test environments to surface double free conditions
Ingest kernel event logs and crash dumps into a centralized data lake for cross-host correlation
Track installed AMD driver versions across the fleet and flag hosts running versions listed as vulnerable in AMD-SB-6018

How to Mitigate CVE-2023-20511

Immediate Actions Required

Inventory endpoints running AMD graphics hardware and identify installed KMD versions
Apply the fixed AMD driver versions as identified in AMD Security Bulletin AMD-SB-6018
Restrict local administrative access to reduce the pool of accounts that satisfy the high-privilege precondition

Patch Information

AMD has published remediation guidance in AMD Security Bulletin AMD-SB-6018. Administrators should deploy the updated AMD graphics driver package on all affected Windows systems. Coordinate driver rollout with OEM channels where AMD drivers are distributed through system vendor update mechanisms.

Workarounds

No official workaround is published; apply the vendor-supplied driver update as the primary remediation
Enforce least privilege so that only trusted administrators can load or interact with kernel drivers
Enable Hypervisor-Protected Code Integrity (HVCI) and Virtualization-Based Security (VBS) to raise the cost of kernel exploitation

bash

# Query installed AMD display driver version on Windows
wmic path win32_VideoController where "Name like '%AMD%'" get Name,DriverVersion,DriverDate

# PowerShell alternative
Get-CimInstance Win32_VideoController | Where-Object { $_.Name -like '*AMD*' } | Select-Object Name,DriverVersion,DriverDate