CVE-2026-45203 Overview
CVE-2026-45203 is a Time-of-Check Time-of-Use (TOCTOU) race condition affecting Imagination Technologies GPU drivers and firmware. Kernel software running inside a Host virtual machine (VM) can post improper commands to the GPU Firmware and trigger memory writes outside the permitted range for the host kernel. A malicious driver modifies values in memory after firmware validation but before those values are consumed. The flaw is tracked under CWE-367 and requires local, low-privileged access to exploit.
Critical Impact
A malicious kernel driver inside a Host VM can bypass GPU firmware validation to write to arbitrary host kernel memory, resulting in loss of confidentiality, integrity, and availability.
Affected Products
- Imagination Technologies GPU drivers exposing firmware command submission from Host VM kernel software
- Systems where guest or host VM kernel components submit commands to the GPU Firmware
- Refer to the Imagination Technologies Driver Vulnerabilities advisory for specific driver versions
Discovery Timeline
- 2026-07-10 - CVE-2026-45203 published to NVD
- 2026-07-13 - Last updated in NVD database
Technical Details for CVE-2026-45203
Vulnerability Analysis
The vulnerability is a classic TOCTOU race condition in the GPU Firmware command submission path. The GPU Firmware validates command buffers or parameter values passed in from the host kernel driver before executing them. Between the validation step and the actual use of those values, a malicious driver mutates the underlying memory. The firmware then acts on unvalidated data and performs a memory write outside the range permitted for the host kernel context.
The result is an out-of-bounds write into host kernel memory, driven from a component that is normally treated as a trusted producer of GPU commands. Because the write is performed by the GPU or its firmware on behalf of the driver, it can bypass CPU-side memory protections that would otherwise contain a rogue kernel module.
Root Cause
The root cause is non-atomic handling of command parameters shared between the kernel driver and the GPU Firmware. Values are checked in one operation and consumed in a later operation without copying to firmware-owned memory or re-validating at use time. This violates the check-then-use invariant described in CWE-367.
Attack Vector
Exploitation requires local access with the ability to load or influence kernel software inside a Host VM. An attacker with a foothold as a low-privileged kernel component races the firmware validator by rewriting command parameters after the check completes. The attacker does not need user interaction, and the attack complexity is low once kernel-mode execution inside the Host VM is achieved.
No public proof-of-concept exploit code is available. Refer to the Imagination Technologies advisory for vendor technical details.
Detection Methods for CVE-2026-45203
Indicators of Compromise
- Unexpected loading of unsigned or non-standard kernel modules that interact with the GPU driver interface inside Host VMs
- Kernel oops, panic, or memory corruption events correlated with GPU command submission activity
- Anomalous host kernel memory writes originating from GPU DMA or firmware execution contexts
Detection Strategies
- Monitor kernel module load events and compare loaded drivers against an approved baseline for Host VM images
- Alert on repeated or high-frequency GPU firmware command submissions from a single process or driver, which can indicate a race-window brute-force pattern
- Correlate GPU driver error logs with kernel integrity events to surface exploitation attempts
Monitoring Recommendations
- Enable kernel integrity monitoring and lockdown modes on Host VMs to detect tampering with driver code and data
- Capture and centralize kernel ring buffer logs, hypervisor logs, and GPU driver telemetry for retention and search
- Track privileged process behavior on Host VMs, focusing on components with access to /dev/dri, GPU ioctl interfaces, or vendor firmware command channels
How to Mitigate CVE-2026-45203
Immediate Actions Required
- Apply the fixed GPU driver and firmware release published in the Imagination Technologies Driver Vulnerabilities advisory
- Restrict the ability to load kernel modules inside Host VMs to a minimum set of signed, vendor-approved drivers
- Audit Host VM images for unauthorized kernel components that interact with the GPU stack
Patch Information
Imagination Technologies publishes fixed driver and firmware versions on the GPU driver vulnerabilities page. Coordinate with the platform vendor or SoC integrator to obtain builds that include the fix, since GPU driver and firmware updates are typically distributed as part of a broader BSP or OS image update.
Workarounds
- Enforce kernel module signature verification and Secure Boot on Host VMs to prevent loading of malicious drivers
- Reduce exposure by disabling GPU passthrough or GPU acceleration for untrusted Host VMs until the patch is deployed
- Apply least privilege to accounts and services that can interact with GPU device nodes and firmware command interfaces
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
