CVE-2025-20632: Mediatek SDK Privilege Escalation Flaw

CVE-2025-20632 Overview

CVE-2025-20632 is an out-of-bounds write vulnerability in the MediaTek WLAN Access Point (AP) driver. The flaw stems from an incorrect bounds check in the driver's handling of wireless data structures. A local attacker with low privileges can trigger the condition to escalate privileges without user interaction. MediaTek tracks the fix under Patch ID WCNCR00397139 and Issue ID MSV-2188. The vulnerability affects multiple MediaTek Wi-Fi chipsets widely deployed in consumer and enterprise networking equipment, including the MT7615, MT7622, MT7663, MT7915, MT7916, MT7981, and MT7986 platforms.

Critical Impact
Local privilege escalation in kernel-space WLAN AP driver code affecting MediaTek Wi-Fi chipsets used across routers, access points, and embedded network devices worldwide.

Affected Products

MediaTek Software Development Kit (SDK)
MediaTek MT7615, MT7622, MT7663 Wi-Fi chipsets
MediaTek MT7915, MT7916, MT7981, MT7986 Wi-Fi chipsets

Discovery Timeline

2025-02-03 - CVE-2025-20632 published to NVD
February 2025 - MediaTek issues Product Security Bulletin with patch WCNCR00397139
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-20632

Vulnerability Analysis

The vulnerability resides in the MediaTek WLAN AP driver code shipped through the MediaTek SDK for MT76-series Wi-Fi chipsets. The driver performs an incorrect bounds check when processing data destined for a fixed-size buffer. The check does not correctly validate the size or index against the actual buffer capacity. As a result, an attacker-controlled value can be written past the intended buffer boundary, corrupting adjacent kernel memory.

Because the WLAN AP driver runs in kernel context on the host system, memory corruption in this component provides a path to arbitrary kernel-mode write. This maps to [CWE-787: Out-of-bounds Write]. The impact assessment covers confidentiality, integrity, and availability, consistent with a full kernel compromise from a local user context.

Root Cause

The root cause is an incorrect bounds check inside a WLAN AP driver routine. The condition guarding the write does not enforce the true upper limit of the destination buffer. Length or index values supplied by a local caller flow into a memory write operation without adequate validation, allowing writes outside the allocated region.

Attack Vector

Exploitation requires local access with low privileges on a system running the affected MediaTek WLAN AP driver, such as an authenticated shell on a router, access point, or embedded Linux device using the MediaTek SDK. No user interaction is required. An attacker interacts with the driver through its standard interface (typically an ioctl or netlink pathway exposed to userland) and supplies crafted input that reaches the vulnerable code path. The subsequent out-of-bounds write can be used to overwrite kernel structures and gain kernel-level code execution, resulting in local escalation of privilege.

No public proof-of-concept exploit has been published, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. See the MediaTek Security Bulletin - February 2025 for vendor technical detail.

Detection Methods for CVE-2025-20632

Indicators of Compromise

Unexpected kernel panics, oops messages, or crashes in dmesg referencing the WLAN AP driver (mt76, mt7615, mt7915, or vendor kernel modules).
New root-owned processes, SUID binaries, or persistence artifacts on network devices that should not run local workloads.
Modification of firmware, boot scripts, or /etc/ configuration on affected access points or routers.

Detection Strategies

Inventory devices by chipset and firmware version and cross-reference against the MediaTek February 2025 bulletin to identify unpatched WLAN AP driver builds.
Monitor kernel logs on OpenWrt, RDK-B, and vendor firmwares for driver faults referencing WLAN AP code paths.
Alert on unexpected local privilege transitions on embedded devices, particularly non-interactive escalation to UID 0.

Monitoring Recommendations

Forward syslog and kernel messages from routers, access points, and embedded gateways to a centralized log platform for anomaly review.
Baseline authorized administrative sessions on network appliances and alert on out-of-band shell activity.
Track firmware and package versions across the fleet to detect devices running vulnerable MediaTek SDK builds.

How to Mitigate CVE-2025-20632

Immediate Actions Required

Apply firmware updates from device vendors that incorporate MediaTek Patch ID WCNCR00397139 addressing Issue ID MSV-2188.
Restrict local shell and management access on affected routers, access points, and embedded devices to trusted administrators only.
Disable unused local services and remote-to-local pivots on network devices to reduce the pool of accounts that could reach the driver interface.

Patch Information

MediaTek published the fix in its February 2025 Product Security Bulletin under Patch ID WCNCR00397139. Device manufacturers integrate this patch into downstream firmware releases for products built on the MT7615, MT7622, MT7663, MT7915, MT7916, MT7981, and MT7986 chipsets. Contact the device OEM for the specific firmware image that includes the fix.

Workarounds

Enforce strong administrative credentials and disable default or shared local accounts on network devices.
Segment management interfaces of routers and access points onto a dedicated VLAN reachable only from administrator workstations.
Where feasible on multi-tenant embedded platforms, restrict access to WLAN driver interfaces (ioctl, netlink sockets) to a narrow set of trusted processes.

bash

# Verify installed firmware version on an OpenWrt-based device using MediaTek chipsets
cat /etc/openwrt_release
opkg list-installed | grep -Ei 'mt76|mt7615|mt7915|mt7981|mt7986'
dmesg | grep -Ei 'mt76|wlan|ap' | tail -n 50