CVE-2026-21736: Imaginationtech DDK Privilege Escalation

CVE-2026-21736 Overview

CVE-2026-21736 affects the Imagination Technologies Graphics Driver Development Kit (DDK). A non-privileged local user can issue improper GPU system calls to gain write access to read-only wrapped user-mode memory. The flaw stems from improper handling of memory protections for the user-mode wrapped memory resource [CWE-280: Improper Handling of Insufficient Permissions or Privileges].

The vulnerability allows authenticated local attackers to modify memory regions that should remain read-only. This can be used to tamper with data integrity or to support further exploitation chains targeting GPU-adjacent processes.

Critical Impact

Local non-privileged users on devices using affected Imagination Technologies DDK builds can bypass read-only memory protections through crafted GPU system calls, undermining memory integrity guarantees.

Affected Products

• Imagination Technologies DDK version 25.1
• Imagination Technologies DDK version 25.1 RTM2
• GPU driver components exposing user-mode wrapped memory resources

Discovery Timeline

• 2026-03-09 - CVE-2026-21736 published to NVD
• 2026-03-10 - Last updated in NVD database

Technical Details for CVE-2026-21736

Vulnerability Analysis

The Imagination Technologies DDK exposes GPU system call interfaces to user-mode applications. One of these interfaces manages wrapped memory resources, which allow user-mode buffers to be referenced by the GPU. The driver maps these resources with specific protection flags that determine whether the GPU and host CPU can read or write the underlying memory.

The vulnerability stems from incorrect enforcement of those protection flags. A non-privileged process can submit crafted system calls that cause the driver to grant write permission to a region originally wrapped as read-only. Because GPUs operate with direct memory access semantics, this discrepancy allows the attacker to modify memory pages that other code paths assume to be immutable.

The weakness is categorized as [CWE-280] because the driver fails to handle insufficient permission state correctly when transitioning resource attributes.

Root Cause

The driver does not consistently propagate or validate the read-only attribute of user-mode wrapped memory across all code paths handling the resource. When the GPU system call updates resource state, the original protection constraint is dropped, permitting writes through the GPU side that were prohibited at wrap time.

Attack Vector

Exploitation requires local access and low privileges. No user interaction is required. An attacker who runs unprivileged code on the device executes a sequence of GPU IOCTLs that target wrapped memory resources, then performs GPU writes to regions the application or kernel marked read-only. The vulnerability does not impact availability but affects confidentiality and integrity at a low level.

The vulnerability is described in vendor advisories. See the Imagination Technologies Driver Vulnerabilities advisory for vendor-supplied technical details.

Detection Methods for CVE-2026-21736

Indicators of Compromise

• Unexpected GPU IOCTL sequences from non-privileged processes targeting wrapped memory resources in the DDK kernel module
• Process activity that repeatedly opens GPU device nodes followed by anomalous memory map operations
• Modifications to memory pages that application logic expects to remain read-only after initial mapping

Detection Strategies

• Monitor user-mode processes that interact with Imagination GPU device interfaces and correlate IOCTL patterns with known wrapped memory abuse sequences
• Audit driver versions in deployed images and flag systems still running DDK 25.1 or 25.1 RTM2
• Apply behavioral analytics to identify unprivileged processes performing GPU memory operations followed by privilege-sensitive actions

Monitoring Recommendations

• Collect kernel telemetry from endpoints with affected GPU drivers and forward to a centralized analytics platform for correlation
• Track driver load events and version metadata for Imagination Technologies kernel modules
• Alert on local privilege escalation attempts that follow GPU IOCTL bursts from the same process tree

How to Mitigate CVE-2026-21736

Immediate Actions Required

• Inventory all devices running Imagination Technologies DDK 25.1 and 25.1 RTM2 and prioritize patching
• Apply the vendor-supplied driver update referenced in the Imagination Technologies advisory as soon as it is available for your platform
• Restrict local access on affected systems to trusted users until patches are deployed

Patch Information

Imagination Technologies publishes driver fixes through its GPU Driver Vulnerabilities portal. Device vendors integrating the DDK distribute corrected builds through their own firmware or system update channels. Verify the installed DDK version after updates to confirm remediation.

Workarounds

• Limit execution of untrusted local code on systems shipping affected DDK builds
• Enforce least-privilege policies and application allowlisting to reduce the population of processes able to issue GPU IOCTLs
• Where feasible, disable or restrict access to GPU device nodes for non-privileged user accounts until patched drivers are installed

# Example: restrict access to GPU device nodes on Linux systems
sudo chgrp gpu-users /dev/dri/renderD128
sudo chmod 0660 /dev/dri/renderD128
# Only members of gpu-users can issue GPU IOCTLs