CVE-2026-20507: Audio HAL Use After Free Vulnerability

CVE-2026-20507 Overview

CVE-2026-20507 is a use-after-free vulnerability in the MediaTek Audio Hardware Abstraction Layer (HAL). The flaw allows a local attacker who already holds System-level privileges to escalate further on affected devices. Exploitation requires no user interaction. MediaTek addressed the issue in Patch ID ALPS11191981, tracked internally as Issue ID MSV-9125. The vulnerability is classified under [CWE-416: Use After Free].

Critical Impact
A local attacker with System privileges can trigger a use-after-free in Audio HAL to escalate privileges further, gaining full control over confidentiality, integrity, and availability on the affected device.

Affected Products

MediaTek chipsets running affected Audio HAL implementations
Android devices integrating MediaTek Audio HAL prior to Patch ID ALPS11191981
See the MediaTek Product Security Bulletin - September 2026 for the full device and chipset list

Discovery Timeline

2026-09-07 - CVE-2026-20507 published to NVD
2026-09-08 - Last updated in NVD database

Technical Details for CVE-2026-20507

Vulnerability Analysis

The vulnerability resides in the Audio HAL component shipped with MediaTek chipsets. Audio HAL bridges the Android audio framework and the underlying vendor audio drivers. A use-after-free condition occurs when the component references memory after it has been released. An attacker holding the System privilege can manipulate object lifetimes within the Audio HAL to reach the freed memory. Successful exploitation yields elevated privileges above the System level, typically enabling access to more sensitive kernel-adjacent contexts or vendor-privileged operations. No user interaction is required, and the attack executes entirely on the local device.

Root Cause

The root cause is improper object lifetime management within the Audio HAL implementation. Code paths retain or reuse pointers to memory regions after those regions have been freed. When the stale pointer is later dereferenced, the attacker-controlled state at the freed location is treated as a valid object. This corresponds to [CWE-416: Use After Free].

Attack Vector

Exploitation is local. The attacker must first obtain the System privilege on the target Android device, typically through a chained vulnerability or a compromised privileged process. From that context, the attacker issues crafted requests to the Audio HAL that trigger the use-after-free and pivot execution or memory access to a higher privilege boundary. MediaTek has not published exploitation details. Refer to the MediaTek Product Security Bulletin - September 2026 for vendor-supplied technical references.

Detection Methods for CVE-2026-20507

Indicators of Compromise

Unexpected crashes or tombstone files referencing Audio HAL processes such as android.hardware.audio service instances
Repeated SIGSEGV or SIGABRT signals originating from Audio HAL worker threads
Devices running MediaTek chipsets without Patch ID ALPS11191981 applied

Detection Strategies

Correlate Android system logs (logcat, dmesg) for anomalous Audio HAL termination events preceded by System-privileged process activity
Monitor for privilege transitions where processes gain capabilities beyond their assigned SELinux domain following audio subsystem interactions
Baseline the security patch level (ro.build.version.security_patch) across the mobile fleet to identify unpatched MediaTek devices

Monitoring Recommendations

Ingest mobile device telemetry and crash reports into a centralized analytics platform for correlation across the fleet
Track vendor patch adoption rates against the MediaTek Product Security Bulletin - September 2026
Alert on any unmanaged application acquiring System-level privileges, which is a prerequisite for exploiting this flaw

How to Mitigate CVE-2026-20507

Immediate Actions Required

Apply the MediaTek security update containing Patch ID ALPS11191981 as soon as it is available through the device manufacturer
Inventory all MediaTek-based Android devices in the environment and identify those missing the September 2026 security patch level
Restrict installation of applications that request or exploit System-level privileges on managed mobile devices

Patch Information

MediaTek released the fix under Patch ID ALPS11191981, tracked as Issue ID MSV-9125. Device manufacturers integrate the patch into their monthly Android security updates. Consult the MediaTek Product Security Bulletin - September 2026 for the authoritative fix guidance and the corresponding OEM release schedule.

Workarounds

No vendor-supplied workaround is documented; patching remains the only supported remediation
Enforce mobile device management (MDM) policies that block sideloading and restrict privileged application installation
Decommission or isolate end-of-life MediaTek devices that will not receive the September 2026 security patch

bash

# Verify the current Android security patch level on a MediaTek device
adb shell getprop ro.build.version.security_patch

# Confirm the vendor and chipset before applying updates
adb shell getprop ro.product.manufacturer
adb shell getprop ro.hardware