CVE-2025-20787: Google Android Use-After-Free Flaw

CVE-2025-20787 Overview

CVE-2025-20787 is a use-after-free vulnerability affecting the display driver component in MediaTek chipsets running Google Android. The vulnerability exists in the display subsystem where memory corruption can occur due to improper memory management after an object has been freed. An attacker who has already obtained System privilege on the device could exploit this flaw to escalate privileges further without requiring any user interaction.

Critical Impact

This vulnerability enables local privilege escalation through memory corruption in the display driver, potentially allowing complete device compromise for attackers with existing System-level access.

Affected Products

• Google Android versions 14.0, 15.0, and 16.0
• MediaTek MT67xx series chipsets (MT6739, MT6761, MT6765, MT6768, MT6781, MT6789, MT6833, MT6835, MT6853, MT6855, MT6877, MT6878, MT6879, MT6883, MT6885, MT6886, MT6889, MT6893, MT6895, MT6897, MT6899, MT6983, MT6985, MT6989, MT6991)
• MediaTek MT27xx series chipsets (MT2718)
• MediaTek MT8xxx series chipsets (MT8196, MT8676, MT8678, MT8796)

Discovery Timeline

• 2026-01-06 - CVE-2025-20787 published to NVD
• 2026-01-08 - Last updated in NVD database

Technical Details for CVE-2025-20787

Vulnerability Analysis

This use-after-free (CWE-416) vulnerability resides in the display driver component of MediaTek chipsets. The flaw occurs when the display subsystem improperly handles memory objects, continuing to reference memory after it has been deallocated. When such freed memory is subsequently accessed, it can lead to memory corruption, which an attacker can leverage to execute arbitrary code or escalate privileges.

The vulnerability is particularly concerning because it requires no user interaction for exploitation. However, the attack is limited to local access and requires the attacker to have already obtained System-level privileges, which serves as a prerequisite condition for exploitation. The display driver operates at a privileged level within the Android kernel space, making successful exploitation especially dangerous as it could allow an attacker to gain kernel-level access or bypass security boundaries.

Root Cause

The root cause of CVE-2025-20787 is improper memory lifecycle management in the MediaTek display driver. Specifically, the driver fails to properly invalidate references to memory objects after they are freed. This creates a dangling pointer scenario where subsequent operations may reference stale memory locations that have been reallocated for other purposes, leading to unpredictable memory corruption.

The vulnerability is tracked internally by MediaTek as Patch ID ALPS10149879 and Issue ID MSV-4658.

Attack Vector

The attack vector for this vulnerability is local, requiring the attacker to have existing access to the device with System-level privileges. The exploitation flow involves:

1. An attacker with System privilege triggers the vulnerable code path in the display driver
2. The display driver incorrectly accesses memory that has already been freed
3. By carefully manipulating memory allocation timing, the attacker can control the contents of the freed memory region
4. When the driver accesses this controlled memory, it can be leveraged to corrupt critical data structures or execute arbitrary code with elevated privileges

The vulnerability can be exploited through specialized applications or kernel modules that interact with the display driver subsystem through available interfaces such as ioctl calls or direct memory manipulation.

Detection Methods for CVE-2025-20787

Indicators of Compromise

• Unusual crashes or instability in the display subsystem or related kernel components
• Unexpected privilege escalation attempts from applications already running with System privileges
• Anomalous memory access patterns in kernel logs related to the display driver
• System instability or spontaneous reboots potentially linked to memory corruption events

Detection Strategies

• Monitor kernel logs for display driver-related memory errors, crashes, or undefined behavior
• Implement kernel integrity monitoring to detect unauthorized privilege escalation
• Deploy mobile threat detection solutions capable of identifying use-after-free exploitation attempts
• Utilize application behavior analysis to identify suspicious interactions with display driver interfaces

Monitoring Recommendations

• Enable verbose logging for the display subsystem to capture potential exploitation attempts
• Implement SELinux/SEAndroid policy monitoring for policy violation alerts
• Configure alerting for unexpected System-level process behavior patterns
• Regularly audit installed applications for excessive permissions or suspicious kernel interactions

How to Mitigate CVE-2025-20787

Immediate Actions Required

• Apply the latest security patches from device manufacturers that include the MediaTek fix (Patch ID: ALPS10149879)
• Ensure devices are running the January 2026 or later Android security patch level
• Limit physical access to affected devices to reduce local attack surface
• Review and restrict applications running with System-level privileges

Patch Information

MediaTek has released a security patch addressing this vulnerability, identified as Patch ID ALPS10149879. The fix is documented in the MediaTek Product Security Bulletin for January 2026. Device manufacturers should integrate this patch into their firmware updates, and end users should apply over-the-air updates as they become available from their respective device vendors.

Workarounds

• Minimize the number of applications granted System-level privileges on affected devices
• Implement additional access controls to restrict interactions with display driver interfaces
• Consider deploying mobile device management (MDM) solutions to enforce security policies
• Monitor for and promptly install vendor-provided security updates

# Check current Android security patch level
adb shell getprop ro.build.version.security_patch

# Verify device chipset to determine if affected
adb shell getprop ro.hardware

# Review applications with elevated privileges
adb shell pm list packages -U | grep system