CVE-2026-0427: GPU Firmware Privilege Escalation Flaw

CVE-2026-0427 Overview

CVE-2026-0427 is a firmware vulnerability affecting AMD GPU products. The flaw stems from improper cleanup of shared register resources in GPU firmware. An admin-privileged attacker operating inside one Guest Virtual Machine (VM) can access shared register resources belonging to another Guest VM on the same host. This cross-tenant exposure can lead to loss of confidentiality, integrity, or availability of data processed by neighboring VMs. The vulnerability is tracked under [CWE-459: Incomplete Cleanup] and was published in the AMD Security Bulletin #6027.

Critical Impact

An admin-privileged attacker in one Guest VM can read or tamper with GPU register state belonging to a co-tenant Guest VM, breaking the isolation boundary that virtualization is expected to enforce.

Affected Products

• AMD GPU products with firmware identified in AMD Security Bulletin #6027
• Virtualized environments using SR-IOV or comparable GPU partitioning on affected AMD hardware
• Multi-tenant Guest VMs sharing GPU resources on affected platforms

Discovery Timeline

• 2026-05-15 - CVE-2026-0427 published to NVD
• 2026-05-15 - Last updated in NVD database

Technical Details for CVE-2026-0427

Vulnerability Analysis

The vulnerability resides in AMD GPU firmware that manages register resources shared across Guest VMs. When a VM relinquishes access to these registers, the firmware does not fully clear or reset the resource state before another VM acquires it. This residual state allows an attacker who already holds administrative privileges inside a Guest VM to observe or manipulate register data left behind by another Guest VM. The result is a cross-VM information leak and a potential tampering primitive within the GPU control plane.

Root Cause

The root cause is incomplete cleanup of shared resources, classified as [CWE-459]. GPU firmware fails to scrub shared register contents during context transitions between Guest VMs. Because the registers persist across tenant boundaries, the firmware effectively leaks state from one VM to another. Proper isolation requires the firmware to zero or re-initialize shared registers whenever ownership changes.

Attack Vector

Exploitation requires local access to a Guest VM and administrative privileges within that VM. The attacker does not need user interaction from the victim VM. The attack vector is local to the hypervisor host because both attacker and victim must share GPU resources on the same physical system. The attacker reads shared registers immediately after a context switch to recover data, or writes attacker-controlled values into shared registers to influence the victim VM's GPU workload.

No public proof-of-concept exploit is available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. For technical specifics, refer to the AMD Security Bulletin #6027.

Detection Methods for CVE-2026-0427

Indicators of Compromise

• Unexpected GPU register reads or writes originating from Guest VMs immediately following a context switch
• Anomalous GPU workload behavior in a Guest VM that correlates with activity in a neighboring VM
• Guest VM administrator accounts performing low-level GPU driver interactions outside normal workload patterns

Detection Strategies

• Audit Guest VM administrative activity targeting GPU driver interfaces and ioctl calls
• Correlate hypervisor GPU scheduling events with in-guest GPU access patterns to spot cross-tenant timing relationships
• Monitor firmware versions across the fleet and flag hosts running unpatched AMD GPU firmware identified in AMD-SB-6027

Monitoring Recommendations

• Centralize hypervisor and Guest VM logs covering GPU device assignment, SR-IOV virtual function allocation, and driver load events
• Alert on Guest VM administrators executing custom or unsigned GPU utilities that interact directly with shared registers
• Track firmware patch status as a continuous configuration metric and flag drift from approved baselines

How to Mitigate CVE-2026-0427

Immediate Actions Required

• Apply the GPU firmware updates referenced in AMD Security Bulletin #6027 on all affected hosts
• Inventory virtualization hosts that expose AMD GPU resources to multiple Guest VMs and prioritize them for patching
• Restrict administrative privileges inside Guest VMs to trusted operators only, since exploitation requires admin rights within a Guest

Patch Information

AMD has published remediation guidance in AMD Security Bulletin #6027. Administrators should follow the bulletin to identify affected GPU models and apply the corresponding firmware versions. Coordinate updates with hypervisor and GPU driver vendors to ensure compatibility across the virtualization stack.

Workarounds

• Avoid sharing a single GPU across mutually untrusted Guest VMs until firmware is updated
• Pin sensitive workloads to dedicated GPU partitions or dedicated hosts to remove cross-tenant exposure
• Limit the number of Guest VM administrators and enforce just-in-time elevation for GPU-adjacent operations

# Configuration example
# Identify AMD GPUs and current firmware on a Linux hypervisor host
lspci -nn | grep -i 'VGA\|3D\|Display'
dmesg | grep -i amdgpu | grep -i firmware

# After applying vendor firmware update, verify version and reload module
modinfo amdgpu | grep -i version
sudo modprobe -r amdgpu && sudo modprobe amdgpu