CVE-2025-20636: Google Android Privilege Escalation Flaw

CVE-2025-20636 Overview

CVE-2025-20636 is an out-of-bounds write vulnerability in the MediaTek secmem (secure memory) component. The flaw stems from a missing bounds check that allows a local actor with System privileges to write outside the intended buffer. Successful exploitation enables local escalation of privilege without user interaction. MediaTek tracks this issue as MSV-2431 and addresses it via patch ALPS09403554. The vulnerability affects a wide range of MediaTek chipsets used in Android 12, 13, 14, and 15 devices. MediaTek published the fix in its February 2025 security bulletin.

Critical Impact

A local attacker who already holds System privileges can write out of bounds in secmem and escalate to higher kernel-level privileges on affected MediaTek-powered Android devices.

Affected Products

• Google Android 12, 13, 14, and 15
• MediaTek chipsets including MT6580, MT6739, MT6761, MT6765, MT6768, MT6779, MT6781, MT6785, MT6789, MT6833, MT6835, MT6853, MT6855, MT6873, MT6877, MT6879, MT6883, MT6885, MT6886, MT6889, MT6893, MT6895, MT6983, MT6985
• MediaTek MT8321, MT8385, MT8666, MT8667, MT8673, MT8755, MT8765, MT8766, MT8768, MT8771, MT8775, MT8781, MT8786, MT8788, MT8789, MT8791T, MT8795T, MT8796, MT8797, MT8798

Discovery Timeline

• 2025-02-03 - CVE-2025-20636 published to NVD
• 2025-02 - MediaTek releases security patch via MediaTek Security Bulletin February 2025
• 2025-03-19 - Last updated in NVD database

Technical Details for CVE-2025-20636

Vulnerability Analysis

The vulnerability resides in the MediaTek secmem driver, which manages secure memory regions used by trusted applications and DRM workflows on MediaTek-powered Android devices. A missing bounds check on attacker-controlled input allows an out-of-bounds write [CWE-787] into adjacent kernel memory. An attacker who already possesses the System privilege on the device can trigger the flaw without any user interaction. The exploitation path is local — there is no remote attack surface. Successful exploitation breaks the trust boundary between the System user and the kernel, enabling privilege escalation beyond the Android sandbox model.

Root Cause

The secmem component fails to validate the size or offset parameters supplied through its driver interface before performing a write operation. Because the bounds check is absent, attacker-controlled values pass directly into the write primitive. This results in memory corruption at locations outside the intended secure-memory buffer.

Attack Vector

Exploitation requires local code execution at the System privilege level, typically achieved by chaining a prior vulnerability or compromising a System-level service. The attacker issues crafted requests to the secmem driver to trigger the unchecked write. No user interaction is required. The technical write-up is available in the MediaTek Security Bulletin February 2025. Patch identifier ALPS09403554 corrects the bounds validation logic in the affected driver.

Detection Methods for CVE-2025-20636

Indicators of Compromise

• Unexpected interactions with the secmem driver interface from non-trusted processes running with System privileges.
• Kernel panics, memory corruption traces, or SELinux denials referencing secmem or related MediaTek driver paths.
• Presence of unauthorized System-level processes performing ioctl operations against secure memory device nodes.

Detection Strategies

• Monitor Android device logs (logcat, dmesg) for kernel oops or crash signatures involving secmem access.
• Inspect installed OTA build numbers against the February 2025 MediaTek security patch level to identify unpatched fleets.
• Use mobile threat defense agents to flag processes attempting to escalate from System to kernel context.

Monitoring Recommendations

• Track Android security patch levels across managed device inventories and alert on devices missing the February 2025 patch.
• Forward mobile device telemetry to a centralized logging platform for anomaly analysis on privileged driver access.
• Enforce attestation policies (Play Integrity, SafetyNet successors) to detect devices in a compromised or rooted state.

How to Mitigate CVE-2025-20636

Immediate Actions Required

• Apply the February 2025 MediaTek security patch (ALPS09403554) to all affected devices through the OEM update channel.
• Identify the Android security patch level on each managed device and prioritize updates for devices running affected MediaTek SoCs.
• Restrict installation of untrusted applications and remove any apps that have escalated to System-level privileges.

Patch Information

MediaTek released the fix in its February 2025 Product Security Bulletin under issue ID MSV-2431 with patch ID ALPS09403554. Device OEMs incorporate this patch into Android security updates aligned with the February 2025 patch level. Refer to the MediaTek Security Bulletin February 2025 for the authoritative advisory and chipset coverage list.

Workarounds

• No vendor-supplied workaround exists; patching is the only supported remediation.
• Reduce risk by limiting which applications and services run with System privileges through enterprise mobility management (EMM) policies.
• Enforce verified boot and disallow rooted or developer-unlocked devices on enterprise networks until patches are confirmed installed.

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

# Confirm MediaTek chipset model
adb shell getprop ro.hardware
adb shell getprop ro.board.platform