CVE-2025-20798 Overview
CVE-2025-20798 is an out-of-bounds write vulnerability [CWE-787] in the MediaTek battery component. The flaw stems from a missing bounds check that allows memory corruption beyond the allocated buffer. Successful exploitation can lead to local escalation of privilege on affected Android devices powered by MediaTek chipsets. Exploitation requires the attacker to already hold System privilege, and no user interaction is needed. MediaTek tracks the fix under Patch ID ALPS10315812 and Issue ID MSV-5533. The vulnerability affects Android 14, 15, and 16 running on a broad range of MediaTek SoCs spanning smartphone, tablet, and embedded platforms.
Critical Impact
A System-privileged attacker can corrupt kernel memory in the battery driver to escalate privileges, potentially achieving full device compromise on affected MediaTek-based Android devices.
Affected Products
- Google Android 14.0, 15.0, and 16.0
- MediaTek smartphone SoCs including MT6765, MT6768, MT6781, MT6833, MT6853, MT6877, MT6893, MT6985, MT6989, and MT6991
- MediaTek tablet and embedded SoCs including MT8186, MT8188, MT8196, MT8676, MT8766, MT8768, MT8781, MT8788e, and MT8893
Discovery Timeline
- 2026-01-06 - CVE-2025-20798 published to NVD
- 2026-01-08 - Last updated in NVD database
- January 2026 - MediaTek publishes Product Security Bulletin with patch ALPS10315812
Technical Details for CVE-2025-20798
Vulnerability Analysis
The vulnerability resides in the MediaTek battery component used in Android kernel drivers across dozens of MediaTek SoCs. A missing bounds check permits a write operation to extend past the boundaries of an allocated buffer, corrupting adjacent kernel memory. This out-of-bounds write [CWE-787] is reachable only after an attacker has obtained System privilege on the device. From that position, an attacker can craft input that overflows the affected buffer and modify kernel data structures. The result is local privilege escalation, typically from System to kernel context, which is the highest privilege boundary on an Android device. Exploitation occurs entirely on the local device and requires no user interaction.
Root Cause
The root cause is the absence of a length or index validation check before a write operation in the battery driver code path. When the driver processes attacker-controlled input, it writes data to a buffer without verifying that the offset or size remains within the allocated region. This permits memory corruption in kernel space.
Attack Vector
The attack vector is local. An attacker must first achieve System privilege through a separate vulnerability or malicious privileged application. Once System access is held, the attacker invokes the affected battery driver interface with crafted parameters that trigger the out-of-bounds write. Successful exploitation yields kernel-level code execution or data tampering, completing the privilege escalation chain.
No verified proof-of-concept code is publicly available. Refer to the MediaTek Security Bulletin January 2026 for vendor-supplied technical context.
Detection Methods for CVE-2025-20798
Indicators of Compromise
- Unexpected kernel panics or crashes referencing the MediaTek battery driver in dmesg or last_kmsg logs
- Privileged processes spawning unexpected child processes or loading unsigned kernel modules after interacting with battery-related sysfs or ioctl interfaces
- Presence of unknown applications holding System UID that access battery driver nodes
Detection Strategies
- Monitor Android device build fingerprints and security patch levels to identify devices missing the January 2026 MediaTek patch level
- Inspect kernel logs for SELinux denials or memory corruption signatures originating from the battery component
- Correlate System-privilege process activity with access to MediaTek vendor driver interfaces to identify anomalous exploitation attempts
Monitoring Recommendations
- Track Android security patch level (SPL) compliance across managed mobile fleets through MDM telemetry
- Enable kernel address sanitizer (KASAN) builds on test devices to catch out-of-bounds writes during validation
- Forward mobile device telemetry to a centralized analytics platform to detect anomalous System-privilege behavior at scale
How to Mitigate CVE-2025-20798
Immediate Actions Required
- Apply the January 2026 MediaTek security patch level on all affected Android devices as soon as the OEM makes it available
- Inventory MediaTek-based devices in the environment against the affected SoC list and prioritize patching for devices that handle sensitive data
- Restrict installation of untrusted applications and revoke unnecessary System-level privileges from third-party packages
Patch Information
MediaTek has released a fix tracked as Patch ID ALPS10315812 and Issue ID MSV-5533. The patch is delivered to OEMs and incorporated into device firmware updates that ship with the January 2026 Android security patch level. Consult the MediaTek Security Bulletin January 2026 for the authoritative list of affected chipsets and patch availability.
Workarounds
- No vendor-supplied workaround is available; patching is the only remediation path
- Reduce risk by enforcing Google Play Protect, blocking sideloading, and removing unnecessary privileged applications until the patch is deployed
- Enforce mobile device compliance policies that quarantine devices running outdated security patch levels from accessing corporate resources
# Verify Android security patch level on a managed device
adb shell getprop ro.build.version.security_patch
# Confirm MediaTek SoC model
adb shell getprop ro.hardware
adb shell getprop ro.board.platform
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
