CVE-2026-46217: Linux Kernel Overflow Vulnerability

CVE-2026-46217 Overview

CVE-2026-46217 is a Linux kernel vulnerability in the AMD GPU (amdgpu) Video Core Next 4 (VCN4) driver. The flaw resides in the message bound check logic, where the previous validation condition was susceptible to integer overflow. Static Defect Logic (SDL) analysis identified the issue, which has been resolved upstream. The fix has been backported to multiple stable kernel branches via cherry-pick from commit 3c5367d950140d4ec7af830b2268a5a6fdaa3885.

Critical Impact
An integer overflow in the VCN4 message boundary validation can allow crafted input to bypass size checks, potentially leading to out-of-bounds memory access within the kernel GPU driver path.

Affected Products

Linux kernel versions containing the drm/amdgpu/vcn4 driver prior to the fix
Distributions shipping affected kernels with AMD GPU hardware support
Stable kernel branches prior to backport of commit 3c5367d9

Discovery Timeline

2026-05-28 - CVE-2026-46217 published to NVD
2026-05-28 - Last updated in NVD database

Technical Details for CVE-2026-46217

Vulnerability Analysis

The vulnerability exists in the drm/amdgpu/vcn4 component of the Linux kernel, which handles Video Core Next generation 4 functionality for AMD graphics processors. The VCN4 driver processes messages submitted from userspace for video encode and decode operations. Before dispatching these messages, the driver validates that the message stays within an expected memory bound.

The original bound check used an arithmetic expression that could overflow when attacker-controlled values were combined. When integer overflow occurs, the result wraps around to a small value, allowing the check to incorrectly conclude that the message fits within bounds. The driver then proceeds to access memory beyond the intended region.

Root Cause

The root cause is an arithmetic boundary computation that did not account for integer overflow [CWE-190]. The unsafe pattern compared offset + size against a buffer limit without first verifying that the addition itself does not wrap. The fix restructures the check so that overflow cases are rejected before bound comparison.

Attack Vector

Exploitation requires the ability to submit VCN messages to the amdgpu driver, which is typically reachable from local userspace processes with access to the DRM device node. A local attacker can craft message parameters that overflow the boundary calculation. See the kernel commit 271cd542 and companion fix 3c5367d9 for the patched logic.

No public proof-of-concept code is available. The vulnerability is described in prose only based on the upstream commit message.

Detection Methods for CVE-2026-46217

Indicators of Compromise

Unexpected kernel oops or GPU hangs originating in the amdgpu_vcn call stack
Kernel log entries referencing VCN message validation failures or DRM scheduler timeouts
Userspace processes repeatedly submitting malformed VCN ioctls to /dev/dri/renderD*

Detection Strategies

Monitor dmesg and journalctl -k for amdgpu errors involving VCN4 message handling
Audit which local users and containers have access to DRM render nodes on AMD GPU hosts
Track kernel package versions against vendor advisories to confirm the patch is applied

Monitoring Recommendations

Forward kernel ring buffer events to a centralized logging platform for correlation
Alert on repeated GPU resets or VCN-related fault traces from a single user session
Inventory hosts running AMD GPUs and verify kernel build hashes against patched references

How to Mitigate CVE-2026-46217

Immediate Actions Required

Update the Linux kernel to a version that includes the upstream fix cherry-picked from commit 3c5367d9
Restrict access to /dev/dri/render* device nodes to trusted local users only
Apply distribution vendor kernel updates as soon as they ship with the backported patch

Patch Information

The fix is available across several stable kernel branches. Reference commits include 271cd542, 30d12ee3, 5bb5faff, 65bce27e, and 73043d29. Apply the kernel package from your distribution that contains these backports.

Workarounds

Limit local user access on AMD GPU systems where kernel updates cannot be applied immediately
Disable hardware video acceleration in untrusted containers and sandboxes that do not require VCN
Use mandatory access controls such as SELinux or AppArmor to restrict DRM device access

bash

# Verify kernel version and confirm patch presence
uname -r
git log --oneline | grep -E "271cd542|3c5367d9|30d12ee3|5bb5faff|65bce27e|73043d29"

# Restrict DRM render node access to a trusted group
chgrp render /dev/dri/renderD128
chmod 0660 /dev/dri/renderD128