CVE-2023-26083

What is the Arm Mali GPU Kernel Driver?

The Arm Mali GPU kernel driver is the privileged kernel-space component that manages hardware resource allocation, memory mapping, and command submission for Arm's Mali family of GPUs (Midgard, Bifrost, and Valhall architectures). Unlike userspace GPU drivers, the kernel driver has direct access to GPU hardware registers and system memory, and it mediates between userspace applications (via the GPU user-space library) and the physical GPU hardware. The Mali GPU kernel driver is integrated into the Linux kernel on Android devices and is responsible for managing GPU job scheduling, memory protection boundaries, and translation table management between the GPU's MMU and the system's physical memory. Information leakage from the kernel driver can expose kernel memory addresses and metadata to unprivileged userspace processes — exactly the type of data needed to defeat kernel ASLR.

Overview

CVE-2023-26083 is an information disclosure vulnerability (CWE-401 — Missing Release of Memory after Effective Lifetime) in the Arm Mali GPU kernel driver affecting Midgard, Bifrost, and Valhall GPU architectures. The vulnerability allows a non-privileged local user to make valid GPU processing operations that expose sensitive kernel metadata — specifically kernel memory addresses — enabling ASLR bypass as a prerequisite for kernel privilege escalation. CISA added CVE-2023-26083 to the KEV catalog on April 7, 2023 — just one day after publication — reflecting that active exploitation was already confirmed at disclosure time.

The 3.3 LOW CVSS score captures the narrow direct impact (information disclosure, local access required, low confidentiality impact) but understates the practical security significance: kernel ASLR bypass transforms a theoretical kernel memory corruption vulnerability into a reliable, weaponizable exploit.

Affected Versions

Note: The fixed driver versions are integrated into Android security updates and device-specific firmware by OEMs — there is no standalone driver package that end users can install directly. The fix reaches end users through Android security patch updates from Google and device OEM firmware updates.

Technical Details

The vulnerability (CWE-401 — memory that is not properly released can contain sensitive data readable by subsequent operations) manifests in the Arm Mali GPU kernel driver's handling of GPU memory objects. When a userspace application submits GPU processing jobs through the kernel driver interface:

1. Kernel allocates GPU memory objects — the driver allocates kernel structures to represent GPU jobs, memory regions, and hardware state, which may contain kernel pointer values and internal metadata
2. Memory is insufficiently sanitized on reuse — the driver fails to completely clear or release certain memory regions between operations; residual kernel-level data (including pointer values that encode the kernel's base address for ASLR) remains accessible
3. Userspace observable leak — a non-privileged process with legitimate access to the GPU (i.e., any app with GPU access, which on Android includes virtually all apps) can submit crafted GPU operations that read back the leaked kernel metadata

The leaked kernel addresses allow an attacker to compute the kernel image base address and the location of key kernel data structures. Armed with this ASLR layout information, a companion kernel memory corruption vulnerability (heap overflow, use-after-free, etc.) can be reliably exploited with precise targeting rather than probabilistic spraying.

Discovery

CVE-2023-26083 was identified by Google's security research teams — consistent with the pattern of Arm Mali GPU vulnerabilities discovered through analysis of exploit chains targeting Android devices. The one-day CISA KEV add (April 7) suggests the vulnerability was observed in active exploitation before or concurrent with public disclosure, likely through forensic analysis of a compromised Android device where the exploit chain was discovered in use.

The extreme speed of KEV addition is a key indicator: standard NVD-tracked vulnerabilities rarely receive same-day or next-day CISA KEV additions — this timing reflects a vulnerability known to be weaponized, not merely patched.

Exploitation Context

CVE-2023-26083 is an exploit chain component — its significance is its role as the ASLR-defeat stage in multi-stage Android kernel exploit chains. Mali GPUs are used in a large proportion of Android devices (particularly Samsung, Google Pixel, and many mid-range Android OEMs), making this a high-value information disclosure primitive.

The exploitation pattern mirrors that of CVE-2023-4211 (Arm Mali UAF, October 2023), CVE-2021-28664, and other Mali GPU kernel vulnerabilities found by Google TAG — which form a sustained series of zero-days discovered being exploited in commercial surveillance vendor (CSV) exploit chains:

1. An attacker achieves unprivileged app code execution (e.g., via a browser exploit or malicious app)
2. The app submits specially crafted GPU operations, exploiting CVE-2023-26083 to leak kernel addresses
3. Armed with the kernel ASLR layout, the attacker exploits a kernel memory corruption vulnerability with precise targeting
4. Kernel privilege escalation yields root access, enabling device takeover, credential theft, and persistent implant installation

The one-day KEV timing and pattern of discovery align with commercial surveillance vendor (spyware) exploit chains targeting activists, journalists, or government officials whose Android devices were forensically analyzed to discover the exploit.

Remediation

1. Apply the relevant Android security patch update — patches for CVE-2023-26083 are distributed through Android security bulletins; update Android devices to the April 2023 or later security patch level (Settings → About phone → Android security patch level).
2. Keep Android devices current with monthly security patches — Arm Mali GPU driver vulnerabilities are a recurring source of zero-day exploits; monthly patch cadence minimizes the exploitation window.
3. Apply MDM minimum patch level enforcement — Mobile Device Management (MDM) policies can enforce minimum Android security patch level requirements for enrolled devices; quarantine or restrict access for devices below the required patch level.
4. Replace devices past end of security support — Android devices that no longer receive security updates from their OEM will not receive Arm Mali GPU driver fixes; replace them with devices receiving current updates.
5. Consider Mobile Threat Defense (MTD) — behavioral detection tools on Android can identify anomalous GPU driver access patterns or unexpected kernel-level activity that may indicate exploit chain execution.