CVE-2025-20763: Google Android Privilege Escalation Flaw

CVE-2025-20763 Overview

CVE-2025-20763 is an out-of-bounds write vulnerability [CWE-787] in the MediaTek mmdvfs (Multimedia Dynamic Voltage and Frequency Scaling) component. The flaw stems from a missing bounds check that allows a local attacker holding System privileges to write outside an allocated buffer. Successful exploitation results in local escalation of privilege on affected Android devices powered by MediaTek chipsets. User interaction is not required for exploitation. MediaTek addressed the issue under Patch ID ALPS10267218 and Issue ID MSV-5032.

Critical Impact

An attacker with System-level privileges can corrupt kernel memory through mmdvfs to escalate to higher-privileged execution contexts on a wide range of MediaTek-based Android smartphones, tablets, and embedded devices.

Affected Products

• Google Android 14.0, 15.0, and 16.0
• MediaTek chipsets including MT6833, MT6853, MT6877, MT6885, MT6893, MT6895, MT6983, MT6985, MT6989, and MT6991
• MediaTek MT8196, MT8676, MT8678, MT8792, MT8793, MT8796, MT8873, and MT8893 platforms

Discovery Timeline

• 2025-12-02 - CVE-2025-20763 published to NVD
• 2025-12-03 - Last updated in NVD database

Technical Details for CVE-2025-20763

Vulnerability Analysis

The vulnerability resides in the mmdvfs driver, which manages dynamic voltage and frequency scaling for multimedia subsystems on MediaTek SoCs. A code path within the driver writes data to a buffer without validating the destination index or size against the buffer boundary. An attacker reaching this code path can write attacker-controlled data past the end of the buffer, corrupting adjacent kernel memory structures.

Because mmdvfs runs in a privileged kernel context, the corruption can be steered into function pointers, credential structures, or kernel object metadata. This enables an attacker who already holds System privileges to pivot into the kernel and obtain higher-privileged execution.

Root Cause

The root cause is a missing bounds check before a memory write operation in the mmdvfs driver. Input parameters supplied to the driver are not validated against the size of the target buffer, producing a classic out-of-bounds write condition consistent with [CWE-787].

Attack Vector

Exploitation requires local access and pre-existing System-level privileges, typically obtained from a compromised privileged application or service. The attacker invokes the vulnerable mmdvfs interface with crafted parameters that drive the write past the buffer boundary. No user interaction is required. The vulnerability cannot be reached remotely or by an unprivileged third-party application without first chaining another flaw.

No public proof-of-concept or in-the-wild exploitation has been reported. Technical details about the specific vulnerable function have not been disclosed in the MediaTek Product Security Bulletin.

Detection Methods for CVE-2025-20763

Indicators of Compromise

• Unexpected kernel panics or device reboots originating from the mmdvfs driver or related multimedia subsystem on MediaTek devices
• Privileged processes (System UID) issuing anomalous ioctl calls toward mmdvfs device nodes
• Newly elevated processes or modified SELinux contexts following activity in a multimedia service

Detection Strategies

• Inventory devices against MediaTek's December 2025 Product Security Bulletin and confirm that Patch ID ALPS10267218 is applied through the device build fingerprint
• Monitor mobile fleet telemetry for kernel crashes referencing mmdvfs symbols and correlate with preceding activity from System-privileged apps
• Use mobile threat defense to flag rooted, unpatched, or out-of-support MediaTek devices accessing corporate resources

Monitoring Recommendations

• Enroll MediaTek-based devices in mobile device management to enforce minimum patch level policies aligned with the December 2025 Android Security Bulletin
• Forward mobile EDR and MDM telemetry into a centralized data lake for correlation of kernel events, privilege transitions, and patch posture across the fleet
• Track Android Security Patch Level (SPL) reporting and alert when devices fall behind the December 2025 baseline

How to Mitigate CVE-2025-20763

Immediate Actions Required

• Apply the vendor patch identified as ALPS10267218 (Issue ID MSV-5032) as soon as the OEM build is available for each affected device model
• Restrict installation of third-party applications that request elevated privileges on MediaTek-based devices until patches are deployed
• Enforce mobile compliance policies that block corporate access from devices below the December 2025 Android Security Patch Level

Patch Information

MediaTek published the fix in the MediaTek Product Security Bulletin – December 2025 under Patch ID ALPS10267218. Device manufacturers integrate this patch into their respective Android security update rollouts. Administrators should confirm that downstream OEM firmware updates carrying this fix are installed across the fleet.

Workarounds

• No vendor-supplied workaround exists; patching through the OEM firmware update channel is the only supported remediation
• Reduce risk by removing or disabling untrusted applications that run with System privileges and by keeping devices enrolled in managed update channels
• Retire end-of-life MediaTek devices that will not receive the December 2025 patch from sensitive workflows

# Verify Android Security Patch Level on a managed device via adb
adb shell getprop ro.build.version.security_patch

# Confirm MediaTek platform identifier to map against the affected chipset list
adb shell getprop ro.board.platform
adb shell getprop ro.hardware