CVE-2026-0027: Google Android Use-After-Free Vulnerability

CVE-2026-0027 Overview

CVE-2026-0027 is a Use After Free vulnerability in the ARM System Memory Management Unit version 3 (SMMU-v3) driver within the Android kernel. Specifically, the flaw exists in the smmu_detach_dev function in arm-smmu-v3.c, where an out-of-bounds write can occur due to improper memory handling after object deallocation. This vulnerability enables local escalation of privilege for attackers who already possess System execution privileges. No user interaction is required to exploit this vulnerability.

Critical Impact

Local privilege escalation via kernel memory corruption in ARM SMMU-v3 driver, requiring System-level privileges but no user interaction.

Affected Products

• Google Android (all versions prior to patch)
• Android kernel with ARM SMMU-v3 driver enabled
• Devices using ARM Cortex-A series processors with SMMU-v3

Discovery Timeline

• 2026-03-02 - CVE-2026-0027 published to NVD
• 2026-03-03 - Last updated in NVD database

Technical Details for CVE-2026-0027

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a critical memory safety issue where the kernel continues to reference memory after it has been freed. In the context of the smmu_detach_dev function, the flaw allows an attacker with System-level execution privileges to trigger an out-of-bounds write operation by exploiting the improper lifecycle management of SMMU device structures.

The ARM SMMU (System Memory Management Unit) is responsible for address translation and memory protection for DMA-capable devices. When a device is detached from the SMMU, the smmu_detach_dev function is called to clean up associated resources. The vulnerability arises when memory associated with the device attachment is freed but subsequently accessed or written to, leading to memory corruption.

Root Cause

The root cause of CVE-2026-0027 lies in the improper synchronization and memory management within the smmu_detach_dev function in arm-smmu-v3.c. When detaching a device from the SMMU, the code fails to properly invalidate or clear references to freed memory structures before they can be accessed again. This creates a window where stale pointers can be dereferenced, leading to use-after-free conditions and subsequent out-of-bounds write operations.

Attack Vector

The attack vector for this vulnerability is local, requiring the attacker to have already achieved System execution privileges on the target Android device. The exploitation pathway involves:

1. The attacker, operating with System privileges, triggers a device detach operation through the SMMU subsystem
2. A race condition or improper cleanup sequence causes the device structure to be freed prematurely
3. The attacker causes the freed memory to be reallocated with attacker-controlled content
4. When the SMMU driver accesses the now-corrupted memory structure, an out-of-bounds write occurs
5. The write operation can overwrite critical kernel data structures, enabling further privilege escalation

Since no user interaction is required, an attacker with initial System access can exploit this vulnerability through automated means. For detailed technical information, refer to the Android Kernel Commit 3af14d2 which addresses this vulnerability.

Detection Methods for CVE-2026-0027

Indicators of Compromise

• Unexpected kernel panics or crashes related to SMMU subsystem operations
• Abnormal memory access patterns in ARM SMMU-v3 driver logs
• System processes exhibiting privilege escalation behavior beyond their normal scope
• Kernel memory corruption signatures in crash dumps referencing arm-smmu-v3.c

Detection Strategies

• Monitor kernel logs for SMMU-related errors, particularly during device attachment/detachment operations
• Implement kernel address sanitizer (KASAN) to detect use-after-free conditions at runtime
• Deploy integrity monitoring solutions to detect unauthorized kernel memory modifications
• Use Android Verified Boot to ensure kernel integrity and detect tampering

Monitoring Recommendations

• Enable comprehensive kernel logging for SMMU subsystem events
• Implement runtime memory corruption detection mechanisms on critical Android deployments
• Monitor for unusual process privilege changes that may indicate exploitation attempts
• Deploy endpoint detection and response (EDR) solutions capable of kernel-level threat detection

How to Mitigate CVE-2026-0027

Immediate Actions Required

• Apply the latest Android security patches from the March 2026 security bulletin immediately
• Prioritize patching devices with ARM SMMU-v3 enabled in enterprise environments
• Implement additional access controls to limit processes that can achieve System execution privileges
• Consider temporarily disabling non-essential DMA devices if patching is delayed

Patch Information

Google has released patches to address CVE-2026-0027 as part of the Android Security Bulletin March 2026. The fix involves proper memory lifecycle management in the smmu_detach_dev function to prevent use-after-free conditions. The following kernel commits address this vulnerability:

• Android Kernel Commit 3af14d2
• Android Kernel Commit 5161b3e
• Android Kernel Commit a47e0e7

Workarounds

• Restrict physical access to affected devices to prevent local exploitation attempts
• Implement strict SELinux policies to limit processes that can interact with the SMMU subsystem
• Enable kernel hardening features such as KASLR (Kernel Address Space Layout Randomization) to make exploitation more difficult
• Monitor and limit applications that require elevated privileges to reduce the attack surface