CVE-2026-21734: Imaginationtech DDK Buffer Overflow Flaw

CVE-2026-21734 Overview

CVE-2026-21734 is an out-of-bounds write vulnerability in the Imagination Technologies DDK (Driver Development Kit) GPU shader compiler. A web page containing unusual GPU shader code loaded into the GPU compiler process triggers a segmentation fault due to a write out-of-bounds condition. The flaw resides in the shader compiler library and is exposed when a very small value in shader code drives the compiler into an unsafe edge case. On platforms where the compiler process runs with system privileges, this crash can be leveraged for further exploitation. The vulnerability affects imaginationtech ddk and is tracked under [CWE-823] (Use of Out-of-range Pointer Offset).

Critical Impact
Local attackers can trigger memory corruption in the GPU shader compiler, potentially enabling privilege escalation on platforms where the compiler runs with system privileges.

Affected Products

Imagination Technologies DDK (all versions prior to fix)
Imagination Technologies DDK version 25.3:rtm
Devices integrating PowerVR GPU drivers based on the affected DDK

Discovery Timeline

2026-06-26 - CVE-2026-21734 published to NVD
2026-06-29 - Last updated in NVD database

Technical Details for CVE-2026-21734

Vulnerability Analysis

The vulnerability resides in the GPU shader compiler component of the Imagination Technologies DDK. When the GPU compiler process parses shader code containing an unusual very-small value, an internal boundary calculation produces an out-of-range pointer offset. The compiler then performs a write to memory outside the intended buffer, causing memory corruption and a segmentation fault. Because shader compilation is triggered by content loaded in a web page, adversarial JavaScript or WebGL/WebGPU code can reach the compiler without user interaction beyond visiting a page. On platforms where the shader compiler executes with elevated or system privileges, controlled corruption of adjacent memory can be escalated beyond a simple denial-of-service outcome.

Root Cause

The root cause is an unchecked edge case in shader code handling where a small numeric input bypasses boundary validation in the compiler's memory management logic. This aligns with [CWE-823], where a pointer offset derived from attacker-controlled shader input falls outside the valid range of the target buffer. The compiler writes to this offset without validating that the resulting address is within the allocated region.

Attack Vector

Exploitation requires local access to the target device. An attacker delivers crafted shader code through a web page that the browser passes to the GPU compiler process for compilation. No authentication or user interaction beyond page load is required. The compiler ingests the malformed shader, performs the faulty computation, and writes out of bounds. Integrity and availability are the primary impacts, with confidentiality unaffected in the base case. Where the compiler process holds system privileges, follow-on exploitation can target kernel or driver structures.

No verified public proof-of-concept code is available. The vulnerability mechanism is described in the Imagination Technologies Vulnerability Overview.

Detection Methods for CVE-2026-21734

Indicators of Compromise

Unexpected segmentation faults or crashes in the GPU shader compiler process following browser navigation
Repeated GPU driver restarts or system stability events after loading web content containing WebGL or WebGPU shaders
Kernel or driver log entries referencing out-of-bounds writes in Imagination Technologies DDK components

Detection Strategies

Monitor process crash telemetry for the GPU compiler service and correlate with recent browser activity or shader compilation events
Instrument endpoints to flag anomalous shader compilation failures originating from untrusted web origins
Review driver-level crash dumps for signatures consistent with [CWE-823] out-of-range pointer offsets in shader compilation routines

Monitoring Recommendations

Enable verbose logging on GPU driver components and forward events to a centralized log platform for correlation
Track browser processes that repeatedly invoke GPU shader compilation with malformed inputs
Alert on privileged process crashes tied to graphics subsystem libraries provided by Imagination Technologies

How to Mitigate CVE-2026-21734

Immediate Actions Required

Inventory all devices using Imagination Technologies PowerVR GPUs and confirm the installed DDK version
Apply vendor-supplied driver updates addressing CVE-2026-21734 as soon as they are made available by the device or SoC manufacturer
Restrict browser access to untrusted sites on affected devices until patches are deployed

Patch Information

Refer to the Imagination Technologies Vulnerability Overview for the authoritative list of fixed DDK versions and coordinated OEM patch availability. Because DDK updates are typically distributed by the SoC vendor or device OEM, downstream update timing depends on the specific device platform.

Workarounds

Disable WebGL and WebGPU in browsers on affected devices where feasible until a driver update is applied
Reduce the privilege level of the GPU compiler process on platforms that permit configuration of driver service accounts
Limit exposure to untrusted web content through browser isolation or web filtering controls

bash

# Example: disable WebGL in Chromium-based browsers via policy
# /etc/chromium/policies/managed/disable-webgl.json
{
  "HardwareAccelerationModeEnabled": false,
  "WebGLEnabled": false
}