CVE-2026-53376: Linux Kernel Privilege Escalation Flaw

CVE-2026-53376 Overview

CVE-2026-53376 is a Linux kernel vulnerability in the AMD Kernel Fusion Driver (amdkfd) component of the Direct Rendering Manager (DRM) subsystem. The flaw resides in kfd_ioctl_get_process_apertures_new, which failed to validate the upper bound of the num_of_nodes value supplied through an IOCTL from user space. Kernel maintainers resolved the issue by adding an explicit upper bound check, cherry-picked from upstream commit 98ff46a5ea090c14d2cdb4f5b993b05d74f3949f.

Critical Impact
A local user issuing a crafted IOCTL to the AMD KFD device could supply an out-of-range num_of_nodes, leading to improper input handling within the kernel driver.

Affected Products

Linux kernel branches containing the drm/amdkfd driver prior to the patched stable releases
Distributions shipping unpatched Linux kernels with AMD KFD (compute) support enabled
Systems exposing /dev/kfd to unprivileged local users on AMD GPU hosts

Discovery Timeline

2026-07-19 - CVE-2026-53376 published to the National Vulnerability Database (NVD)
2026-07-20 - Last updated in NVD database

Technical Details for CVE-2026-53376

Vulnerability Analysis

The vulnerability affects the kfd_ioctl_get_process_apertures_new handler in the drm/amdkfd driver. This IOCTL returns per-node aperture information to user-space compute clients using the Heterogeneous System Architecture (HSA) interface exposed by AMD GPUs. Callers supply a num_of_nodes field indicating how many node entries they expect to retrieve.

The handler validated that num_of_nodes was not zero but did not enforce an upper bound before using the value to iterate and copy data. A local process with access to the KFD character device could pass an oversized value, causing the kernel to process more entries than the driver actually supports. The fix adds an explicit upper bound check against the maximum supported node count.

Root Cause

The root cause is improper input validation on a user-controlled length field crossing the user-kernel trust boundary. The IOCTL parser accepted num_of_nodes without comparing it against NUM_OF_SUPPORTED_GPUS or the equivalent driver-defined ceiling. This is a classic missing bounds check pattern in a kernel driver IOCTL path.

Attack Vector

Exploitation requires local access and the ability to open the KFD device node, typically /dev/kfd. An attacker invokes the affected IOCTL with an inflated num_of_nodes argument. Because the attack surface is a kernel driver reachable from user space, any process granted access to the compute device on an AMD GPU host is in scope. Remote exploitation is not applicable. The patched kernels reject out-of-range values before further processing occurs.

No verified public proof-of-concept code is available at time of writing. Refer to the upstream commits 44d5a45, 4a8093c, 6ba6ec5, 74b73fa, and 7b80137 for the exact patch content.

Detection Methods for CVE-2026-53376

Indicators of Compromise

Unexpected process crashes, kernel warnings, or oops entries referencing kfd_ioctl_get_process_apertures_new in dmesg or /var/log/kern.log
Non-GPU-workload processes opening /dev/kfd and issuing KFD_IOC_GET_PROCESS_APERTURES_NEW
Unprivileged users invoking KFD IOCTLs on servers where GPU compute is limited to specific service accounts

Detection Strategies

Audit installed kernel packages against the fixed versions referenced in the linked stable kernel commits
Monitor auditd rules on /dev/kfd open and ioctl syscalls to identify unexpected callers
Correlate kernel ring buffer messages from the amdgpu and amdkfd subsystems with process telemetry to spot anomalous IOCTL patterns

Monitoring Recommendations

Enable kernel taint and warning capture forwarding to a central log store for retrospective analysis
Track kernel version drift across GPU compute nodes to identify hosts still running vulnerable builds
Alert on new local processes accessing GPU device nodes outside of expected workload identities

How to Mitigate CVE-2026-53376

Immediate Actions Required

Inventory Linux hosts with AMD GPUs and the amdkfd module loaded, then prioritize patching those exposing /dev/kfd to multi-tenant users
Apply the vendor-provided kernel update containing the upstream fix as soon as it is available for your distribution
Restrict access to /dev/kfd to trusted service accounts through group ownership and udev rules where compute workloads permit

Patch Information

The fix has been merged into the stable Linux kernel tree and backported across multiple maintenance branches. Rebuild or install kernel packages that include one of the following commits: Kernel Commit 44d5a45, Kernel Commit 4a8093c, Kernel Commit 6ba6ec5, Kernel Commit 74b73fa, and Kernel Commit 7b80137.

Workarounds

Unload the amdkfd module on hosts that do not require AMD GPU compute using modprobe -r amdkfd, and blacklist it where feasible
Tighten permissions on /dev/kfd so that only known compute workloads can open the device
Where GPU compute is required, isolate untrusted tenants from bare-metal access using virtualization or dedicated hosts until patched kernels are deployed

bash

# Example: restrict access to the AMD KFD device via udev
# /etc/udev/rules.d/70-kfd.rules
KERNEL=="kfd", GROUP="gpu-compute", MODE="0660"

# Verify the running kernel includes the fix
dmesg | grep -i amdkfd
uname -r