CVE-2025-20654: Mediatek SDK RCE Vulnerability

CVE-2025-20654 Overview

CVE-2025-20654 is a critical out-of-bounds write vulnerability affecting MediaTek's WLAN service component. The vulnerability exists due to an incorrect bounds check, which could allow an attacker to write data beyond the intended buffer boundaries. This flaw enables remote code execution without requiring any user interaction or additional execution privileges, making it particularly dangerous for affected network devices and routers.

Critical Impact

This vulnerability allows unauthenticated remote attackers to execute arbitrary code on affected MediaTek-based devices through the WLAN service, potentially compromising network infrastructure including routers and access points running OpenWrt.

Affected Products

• MediaTek Software Development Kit
• MediaTek MT7622
• MediaTek MT7915
• MediaTek MT7916
• MediaTek MT7981
• MediaTek MT7986
• MediaTek MT6890
• OpenWrt 19.07.0 and 21.02.0

Discovery Timeline

• 2025-04-07 - CVE-2025-20654 published to NVD
• 2025-04-09 - Last updated in NVD database

Technical Details for CVE-2025-20654

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-Bounds Write), a memory corruption flaw that occurs when the WLAN service fails to properly validate buffer boundaries before writing data. The incorrect bounds check allows an attacker to write data beyond the allocated memory region, potentially overwriting critical memory structures such as function pointers, return addresses, or other security-sensitive data.

The network-accessible nature of the WLAN service means this vulnerability can be exploited remotely without authentication. No user interaction is required, and the attacker does not need any privileges on the target system. Successful exploitation results in complete compromise of the affected device with full control over confidentiality, integrity, and availability.

Root Cause

The root cause is an incorrect bounds check within the MediaTek WLAN service. When processing network data, the service fails to properly validate the size or boundaries of input before writing to memory buffers. This insufficient validation allows malicious input to trigger a write operation beyond the intended memory boundaries, leading to memory corruption. The specific issue is tracked internally by MediaTek as Patch ID: WCNCR00406897 and Issue ID: MSV-2875.

Attack Vector

The attack vector is network-based, targeting the WLAN service exposed on vulnerable MediaTek chipsets. An attacker can send specially crafted network packets to the vulnerable device that exploit the incorrect bounds check. Since no authentication or user interaction is required, attackers can target any exposed device running the vulnerable WLAN service. This is particularly concerning for networking equipment such as routers and access points that are directly exposed to network traffic.

The vulnerability affects multiple MediaTek Wi-Fi chipsets commonly found in consumer and enterprise networking equipment, as well as OpenWrt installations using MediaTek hardware, significantly expanding the potential attack surface.

Detection Methods for CVE-2025-20654

Indicators of Compromise

• Unexpected crashes or reboots of affected networking devices
• Anomalous memory consumption patterns in the WLAN service
• Unusual network traffic patterns targeting wireless management interfaces
• Unauthorized configuration changes on affected devices
• Evidence of arbitrary code execution in system logs

Detection Strategies

• Monitor network traffic for malformed or oversized WLAN management frames
• Implement network-based intrusion detection signatures for exploitation attempts
• Deploy endpoint detection on devices with visibility into MediaTek WLAN service behavior
• Review firmware versions to identify devices running vulnerable MediaTek SDK versions

Monitoring Recommendations

• Enable verbose logging on affected network devices where supported
• Monitor for unauthorized access attempts to device management interfaces
• Implement network segmentation to isolate potentially vulnerable networking equipment
• Track firmware update status across all MediaTek-based devices in the environment

How to Mitigate CVE-2025-20654

Immediate Actions Required

• Apply the security patch from MediaTek as referenced in Patch ID WCNCR00406897
• Upgrade OpenWrt installations to versions that include the MediaTek security fix
• Isolate affected devices from untrusted networks until patching is complete
• Review and restrict network access to WLAN management interfaces
• Monitor affected devices for signs of compromise

Patch Information

MediaTek has released a security patch to address this vulnerability. The patch is documented in the MediaTek Security Bulletin April 2025. Users of affected devices should contact their device manufacturer for firmware updates that incorporate this patch. OpenWrt users should update to the latest available release that includes the MediaTek security fix.

Workarounds

• Restrict network access to affected devices using firewall rules or network segmentation
• Disable unnecessary wireless management features if supported by the device firmware
• Place affected devices behind additional network security controls
• Consider replacing affected devices if vendor patches are not available

# Example: Network segmentation using firewall rules
# Block external access to WLAN management interfaces
iptables -A INPUT -i wan -p udp --dport 5246 -j DROP
iptables -A INPUT -i wan -p udp --dport 5247 -j DROP

# Restrict management access to trusted networks only
iptables -A INPUT -s 192.168.1.0/24 -j ACCEPT
iptables -A INPUT -j DROP