CVE-2026-7639: GPU Driver Use-After-Free Vulnerability

CVE-2026-7639 Overview

CVE-2026-7639 is a use-after-free vulnerability in an Imagination Technologies GPU driver. A non-privileged local user can issue a crafted sequence of GPU system calls that triggers a failure path in the Memory Management Unit (MMU) mapping logic. The failure leaves internal driver state improperly cleaned up, classified under [CWE-459] Incomplete Cleanup. Shader code running under the attacker's control can then reach freed memory regions and read or modify physical memory outside the attacker's process boundary. The flaw affects confidentiality, integrity, and availability of the host system.

Critical Impact
A local, low-privileged process can leverage improper GPU driver cleanup to access arbitrary physical memory contents from shader code, enabling privilege escalation and data disclosure.

Affected Products

Imagination Technologies GPU DDK (Driver Development Kit)
Systems shipping PowerVR/IMG GPU drivers exposed to the referenced advisory
Devices integrating the affected Imagination GPU kernel driver stack

Discovery Timeline

2026-07-10 - CVE-2026-7639 published to the National Vulnerability Database
2026-07-13 - Last updated in the NVD database

Technical Details for CVE-2026-7639

Vulnerability Analysis

The defect lives in the GPU driver's MMU mapping logic. When a userland process issues GPU system calls, the driver builds and tears down GPU page-table structures that back buffer objects used by shaders. A specific sequence of calls forces the mapping code into an error path. On that path, the driver releases underlying physical pages but fails to fully invalidate the internal state that tracks those mappings.

The result is a classic use-after-free condition ([CWE-459]). GPU page-table entries or driver bookkeeping still reference memory that the kernel has returned to the general allocator. Subsequent allocations reuse those physical pages for unrelated kernel or user data. Because the stale GPU mappings persist, shader code submitted by the unprivileged attacker can read or write those physical pages directly through the GPU.

This bypasses the memory isolation that the operating system enforces between processes and between userland and kernel space. Local privilege escalation, credential theft, and kernel data tampering are all realistic outcomes.

Root Cause

The root cause is incomplete cleanup on an error path inside the MMU mapping routine. The driver does not atomically unmap and invalidate GPU page tables before releasing the backing physical pages when a mid-sequence failure occurs, leaving dangling references from the GPU's view of memory.

Attack Vector

Exploitation requires local access with low privileges and no user interaction. The attacker executes a program that opens the GPU device node, issues a crafted sequence of allocation and mapping ioctls to trigger the failure path, then submits shader workloads that dereference the now-stale GPU virtual addresses to touch arbitrary physical memory. Refer to the Imagination Tech GPU Driver Vulnerabilities advisory for vendor-supplied technical detail.

Detection Methods for CVE-2026-7639

Indicators of Compromise

Unprivileged processes repeatedly opening the GPU device node (for example /dev/dri/renderD* or vendor-specific /dev/pvr_sync) and issuing high volumes of allocation/mapping ioctls.
Kernel log entries referencing MMU mapping failures, page table teardown errors, or GPU fault messages originating from the Imagination driver.
Unexpected GPU workloads submitted by non-graphical user sessions or headless service accounts.

Detection Strategies

Monitor for user processes issuing atypical sequences of GPU ioctls followed by shader submissions, especially from binaries outside standard graphics stacks.
Correlate kernel ring-buffer errors from the GPU driver with process execution telemetry to identify pre-exploitation reconnaissance.
Baseline legitimate GPU consumers on each host and alert on deviations in caller identity or call cadence.

Monitoring Recommendations

Forward dmesg and audit logs to a centralized analytics platform and build detections around MMU error strings from the vendor driver.
Track process lineage for any binary that opens GPU character devices from non-interactive contexts.
Alert on new or unsigned executables invoking GPU compute APIs shortly after landing on a host.

How to Mitigate CVE-2026-7639

Immediate Actions Required

Inventory all systems running Imagination Technologies GPU drivers, including embedded and mobile-class hardware, and prioritize multi-tenant hosts.
Apply vendor-supplied driver updates referenced in the Imagination Tech GPU Driver Vulnerabilities advisory as soon as they are available for your platform.
Restrict access to GPU device nodes so that only trusted user accounts and services can submit workloads.

Patch Information

Imagination Technologies publishes fixed DDK versions and integration guidance on its GPU driver vulnerabilities page. Downstream SoC vendors and operating system distributors must consume the corrected driver and ship it through their firmware or kernel update channels. Consult the vendor advisory for the specific DDK release that resolves the incomplete cleanup in the MMU mapping path.

Workarounds

Where patching is not immediately possible, remove or tighten permissions on GPU device files to block untrusted local users from invoking the vulnerable ioctls.
Disable GPU compute or shader submission for workloads that do not require it, particularly on shared or kiosk systems.
Isolate untrusted code in virtual machines or sandboxes that do not expose the host GPU driver interface.

bash

# Configuration example: restrict access to GPU render nodes to the 'video' group
sudo chgrp video /dev/dri/renderD*
sudo chmod 0660 /dev/dri/renderD*
# Remove untrusted users from the group that can submit GPU work
sudo gpasswd -d untrusted_user video