CVE-2025-20776: Google Android Privilege Escalation Flaw

CVE-2025-20776 Overview

CVE-2025-20776 is an out-of-bounds read vulnerability in the display driver component of MediaTek chipsets running Google Android. The flaw stems from a missing bounds check in the display subsystem, which could allow an attacker who has already obtained System-level privileges to escalate their access further. Notably, this vulnerability does not require user interaction for exploitation, making it particularly concerning for devices with compromised system processes.

This vulnerability is classified as CWE-125 (Out-of-Bounds Read) and affects a wide range of MediaTek mobile and tablet chipsets across Android versions 14.0, 15.0, and 16.0. With a CVSS score of 6.7 (MEDIUM), the vulnerability requires local access and high privileges but can result in significant confidentiality, integrity, and availability impacts.

Critical Impact

Local privilege escalation vulnerability in MediaTek display driver affecting 45+ chipsets across Android 14, 15, and 16, enabling attackers with System privileges to potentially gain additional elevated access without user interaction.

Affected Products

• Google Android 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 MT81xx/MT87xx series chipsets (MT8186, MT8188, MT8196, MT8667, MT8673, MT8676, MT8678, MT8765, MT8766, MT8768, MT8771, MT8781, MT8791T, MT8792, MT8793, MT8795T, MT8796, MT8798, MT8873, MT8883)

Discovery Timeline

• 2025-12-02 - CVE-2025-20776 published to NVD
• 2025-12-03 - Last updated in NVD database

Technical Details for CVE-2025-20776

Vulnerability Analysis

The vulnerability exists within the display driver component of MediaTek chipsets. A missing bounds check allows an out-of-bounds read operation to occur during display-related processing. The CVSS vector CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H indicates that while the attack vector is local and requires high privileges (System-level access), successful exploitation can lead to high impacts across all three security dimensions: confidentiality, integrity, and availability.

The vulnerability is tracked internally by MediaTek under Patch ID ALPS10184297 and Issue ID MSV-4759. According to the EPSS (Exploit Prediction Scoring System), this vulnerability has a 0.005% probability of exploitation, placing it in the 24.3rd percentile of scored vulnerabilities.

Root Cause

The root cause of CVE-2025-20776 is a missing bounds check in the display driver code. When processing certain display-related data structures or buffers, the driver fails to properly validate the boundaries of memory access operations. This oversight allows read operations to extend beyond the intended buffer boundaries, potentially accessing adjacent memory regions that may contain sensitive data or critical system structures.

Out-of-bounds read vulnerabilities in kernel-level drivers like display drivers are particularly dangerous because they operate with elevated privileges and have direct access to system memory. The lack of proper input validation in the display subsystem creates an exploitable condition when specific data patterns are processed.

Attack Vector

The attack vector for this vulnerability is local, meaning an attacker must have existing access to the device. The exploitation scenario requires:

1. Pre-existing System Privileges: The attacker must have already compromised the device to the point of obtaining System-level privileges through another vulnerability or attack chain
2. Local Access: The attack cannot be performed remotely; the malicious code must execute on the target device
3. No User Interaction: Once the attacker has the required privileges, exploitation can proceed without any action from the device user

The attacker would craft specific inputs to the display driver that trigger the out-of-bounds read condition. The vulnerability mechanism involves improper memory access during display buffer operations. When the display driver processes certain data without proper bounds validation, it reads beyond allocated memory boundaries. This can expose sensitive kernel memory contents or enable further exploitation techniques. Technical details are available in the MediaTek security bulletin referenced below.

Detection Methods for CVE-2025-20776

Indicators of Compromise

• Unusual system crashes or display driver failures without apparent cause
• Anomalous memory access patterns in kernel logs related to the display subsystem
• Unexpected privilege escalation events on devices with MediaTek chipsets
• System logs showing display driver errors with memory access violations

Detection Strategies

Organizations can implement several detection strategies to identify potential exploitation attempts:

Kernel-Level Monitoring: Deploy endpoint detection solutions capable of monitoring kernel-level memory operations. Look for anomalous read patterns in display driver contexts that may indicate out-of-bounds access attempts.

Android Audit Logging: Enable comprehensive audit logging on Android devices to capture privilege escalation events and unusual system service behavior. Monitor for processes attempting to access display driver interfaces in unexpected ways.

Behavioral Analysis: Implement behavioral analysis tools that can detect unusual sequences of operations involving the display subsystem, particularly when combined with privilege manipulation attempts.

Mobile Device Management (MDM): Use MDM solutions to monitor device health, patch status, and security events across managed Android devices with affected MediaTek chipsets.

Monitoring Recommendations

Security teams should implement continuous monitoring for devices running affected MediaTek chipsets:

1. Patch Compliance Monitoring: Track the patch status of all Android devices with affected MediaTek chipsets to ensure the December 2025 security updates are applied
2. Security Event Correlation: Correlate display driver events with other security indicators to identify potential multi-stage attacks
3. Threat Intelligence Integration: Subscribe to MediaTek and Android security bulletins to stay informed about related vulnerabilities and emerging threats
4. Endpoint Telemetry: Collect and analyze endpoint telemetry from mobile devices, focusing on kernel-level operations and privilege changes

How to Mitigate CVE-2025-20776

Immediate Actions Required

• Apply the December 2025 MediaTek security patch (Patch ID: ALPS10184297) immediately on all affected devices
• Prioritize patching for devices with sensitive data or in high-risk environments
• Review and restrict applications with System-level privileges on affected devices
• Monitor devices for signs of compromise while patches are being deployed

Patch Information

MediaTek has released a security patch addressing this vulnerability in their December 2025 Product Security Bulletin. The patch is identified by:

• Patch ID: ALPS10184297
• Issue ID: MSV-4759

The patch adds proper bounds checking to the display driver to prevent out-of-bounds read operations. Organizations should work with their device manufacturers or carriers to obtain and deploy the updated firmware. The official security bulletin is available at the MediaTek Product Security Bulletin page.

For enterprise environments, coordinate with MDM solutions to push security updates to managed devices. Consumer users should check for system updates through their device settings and install any available security patches promptly.

Workarounds

Since this vulnerability requires System-level privileges for exploitation, organizations can implement several defensive measures while awaiting patch deployment:

1. Minimize Attack Surface: Reduce the number of applications and services running with elevated privileges on affected devices
2. Application Vetting: Implement strict application vetting procedures to prevent installation of potentially malicious apps that could be used in attack chains
3. Device Isolation: Consider isolating high-value devices or those handling sensitive data until patches can be applied
4. Enhanced Monitoring: Deploy additional monitoring on affected devices to detect potential exploitation attempts

# Android ADB commands to check device security patch level
adb shell getprop ro.build.version.security_patch
# Expected output after patching: 2025-12-05 or later

# Check MediaTek chipset model
adb shell getprop ro.hardware
# Verify against affected chipset list