CVE-2025-20802: Google Android Use-After-Free Vulnerability

CVE-2025-20802 Overview

CVE-2025-20802 is a use-after-free vulnerability [CWE-416] in the MediaTek geniezone component used in Android devices. The flaw enables local privilege escalation when an attacker has already obtained System-level privilege. Exploitation requires no user interaction. MediaTek tracks the fix under Patch ID ALPS10238968 and Issue ID MSV-4914.

The vulnerability affects multiple MediaTek system-on-chip (SoC) platforms running Google Android, including mt6991, mt8196, mt8367, mt8781, mt8786, and mt8793. MediaTek published remediation details in its January 2026 Product Security Bulletin.

Critical Impact
A local attacker with System privilege can corrupt kernel memory in the geniezone trusted execution environment driver, leading to escalation beyond the Android sandbox and potential compromise of secure-world assets.

Affected Products

Google Android 15.0
MediaTek SoCs: mt6991, mt8196, mt8367
MediaTek SoCs: mt8781, mt8786, mt8793

Discovery Timeline

2026-01-06 - CVE-2025-20802 published to NVD
2026-01-06 - MediaTek releases security patch (Patch ID ALPS10238968)
2026-01-08 - Last updated in NVD database

Technical Details for CVE-2025-20802

Vulnerability Analysis

The vulnerability resides in geniezone, MediaTek's hypervisor-based trusted execution environment (TEE) component. GenieZone provides isolated execution for security-sensitive workloads on MediaTek chipsets. A use-after-free condition in this component allows memory previously freed to be referenced again, producing memory corruption that an attacker can shape into arbitrary kernel-mode behavior.

The attack surface is local. An attacker must already hold System privilege on the device to invoke the vulnerable code path. Successful exploitation breaches the boundary between the Android System context and the GenieZone kernel/hypervisor context, exposing confidentiality, integrity, and availability of secure-world resources.

Root Cause

The root cause is a use-after-free [CWE-416] in the geniezone driver. The component retains a reference to a memory object after that object has been released. Subsequent operations dereference the stale pointer, allowing controlled data to occupy the reused allocation. This pattern typically arises from missing reference counting, incorrect lifecycle handling between IOCTL calls, or race conditions in concurrent handlers.

Attack Vector

Exploitation proceeds through interaction with the geniezone kernel driver from a process holding System privilege. The attacker triggers allocation, frees the underlying object, and then reuses the dangling reference through a follow-up driver request. By spraying the heap with attacker-controlled data, the freed slot can be reclaimed with crafted contents. The driver then operates on those contents as if they were valid kernel structures, achieving kernel-context corruption. No user interaction is required.

Detection Methods for CVE-2025-20802

Indicators of Compromise

Unexpected kernel panics or geniezone driver crashes in dmesg or Android bug reports.
Anomalous IOCTL traffic from System-privileged processes targeting the geniezone device node.
Unsigned or unexpected modules loaded after geniezone-related faults.
Build fingerprints on affected MediaTek SoCs that lack the January 2026 patch level.

Detection Strategies

Monitor mobile device patch level against the Android Security Bulletin and MediaTek bulletin for January 2026.
Inspect crash telemetry for repeated faults referencing geniezone symbols, which can indicate exploitation attempts.
Correlate System-context process behavior with subsequent kernel-level anomalies to identify privilege boundary breaches.

Monitoring Recommendations

Enroll managed Android devices into a mobile device management (MDM) solution that reports security patch levels.
Forward kernel and logcat telemetry from fleet devices to a central analytics pipeline for anomaly review.
Track MediaTek security bulletins and Android monthly updates for the affected SoC families.

How to Mitigate CVE-2025-20802

Immediate Actions Required

Apply the January 2026 MediaTek security patch (ALPS10238968) through the device vendor's OTA channel.
Update affected Android devices to a security patch level that incorporates the MediaTek January 2026 bulletin fixes.
Audit installed applications and remove any that hold or attempt to obtain System-level privileges without justification.

Patch Information

MediaTek addressed the use-after-free under Patch ID ALPS10238968, Issue ID MSV-4914. Distribution depends on the device OEM integrating the patch into their Android build and shipping it via OTA. Refer to the MediaTek Security Bulletin January 2026 for the authoritative advisory.

Workarounds

No vendor-supplied workaround is documented. Patching is the supported remediation.
Restrict installation of applications that could acquire System privilege through preloaded OEM packages or sideloading.
Enforce mobile application vetting policies via MDM to limit exposure on unpatched devices.

bash

# Verify Android security patch level on a managed device
adb shell getprop ro.build.version.security_patch
adb shell getprop ro.product.board
adb shell getprop ro.hardware