CVE-2025-20633: Mediatek SDK RCE Vulnerability

CVE-2025-20633 Overview

CVE-2025-20633 is an out-of-bounds write vulnerability discovered in the MediaTek WLAN AP driver. The vulnerability stems from an incorrect bounds check that allows attackers within adjacent network range to execute arbitrary code on affected devices without requiring user interaction or additional execution privileges.

This firmware vulnerability affects multiple MediaTek chipsets commonly found in wireless access points and networking equipment. The flaw exists in the driver's handling of certain inputs, where improper boundary validation enables memory corruption through adjacent network access.

Critical Impact

Adjacent network attackers can achieve remote code execution on vulnerable MediaTek wireless chipsets without authentication or user interaction, potentially compromising network infrastructure devices.

Affected Products

• MediaTek Software Development Kit
• MediaTek MT7603
• MediaTek MT7615
• MediaTek MT7622
• MediaTek MT7915

Discovery Timeline

• 2025-02-03 - CVE-2025-20633 published to NVD
• 2025-03-18 - Last updated in NVD database

Technical Details for CVE-2025-20633

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-Bounds Write), a memory corruption issue where data is written beyond the boundaries of an allocated buffer. In the context of the MediaTek WLAN AP driver, the vulnerability occurs due to an incorrect bounds check when processing wireless network data.

The adjacent network attack vector means an attacker must be within wireless range of the vulnerable access point to exploit this vulnerability. Once exploited, the attacker can achieve code execution with the privileges of the wireless driver, which typically runs in a privileged kernel context on embedded networking devices.

The vulnerability requires no authentication (PR:N) and no user interaction (UI:N), making it particularly dangerous for exposed wireless infrastructure. The impact spans all three security dimensions—confidentiality, integrity, and availability—as successful exploitation grants complete control over the affected device.

Root Cause

The root cause is an incorrect bounds check in the WLAN AP driver code. When processing wireless network frames or management data, the driver fails to properly validate the size or length of input data before writing it to a fixed-size buffer. This allows an attacker to craft malicious wireless packets that, when processed by the driver, write data beyond the intended memory boundary.

This type of vulnerability is common in embedded firmware and driver code where performance optimizations sometimes lead to insufficient input validation. The MediaTek patch (ID: WCNCR00400889) addresses this by implementing proper boundary validation.

Attack Vector

The attack vector is adjacent network, meaning exploitation requires the attacker to be within wireless communication range of the vulnerable device. The attack flow involves:

1. An attacker positions themselves within wireless range of a device using a vulnerable MediaTek chipset (MT7603, MT7615, MT7622, or MT7915)
2. The attacker transmits specially crafted wireless frames designed to trigger the bounds check flaw
3. The vulnerable driver processes these frames without proper validation
4. Data is written beyond the allocated buffer boundary, corrupting adjacent memory
5. By carefully controlling the overflow data, the attacker achieves code execution in the driver context

The proximity requirement provides some natural limitation, but public-facing access points in retail, hospitality, or enterprise environments remain at significant risk from attackers in physical proximity.

Detection Methods for CVE-2025-20633

Indicators of Compromise

• Unexpected crashes or reboots of wireless access points using affected MediaTek chipsets
• Anomalous wireless traffic patterns or malformed 802.11 frames in wireless network captures
• Unusual process execution or network connections originating from wireless infrastructure devices
• Memory corruption artifacts or kernel panic logs referencing the WLAN driver

Detection Strategies

• Monitor wireless network traffic for malformed or oversized management frames targeting access points
• Implement firmware integrity monitoring on networking devices to detect unauthorized modifications
• Deploy network anomaly detection to identify unusual behavior from access point IP addresses
• Review device logs for driver crashes, memory errors, or unexpected restarts

Monitoring Recommendations

• Enable verbose logging on wireless access points where supported to capture driver-level events
• Configure SIEM alerts for patterns indicating wireless infrastructure compromise
• Establish baseline network behavior for access points to detect anomalous outbound connections
• Conduct regular firmware version audits to ensure devices are running patched versions

How to Mitigate CVE-2025-20633

Immediate Actions Required

• Identify all devices in your environment using affected MediaTek chipsets (MT7603, MT7615, MT7622, MT7915)
• Apply the security patch from MediaTek (Patch ID: WCNCR00400889) as soon as vendor firmware updates are available
• Implement network segmentation to isolate wireless infrastructure from critical network segments
• Monitor affected devices for signs of compromise while awaiting patch deployment

Patch Information

MediaTek has released a security patch addressing this vulnerability. The patch is tracked as Patch ID: WCNCR00400889 and Issue ID: MSV-2491. Organizations should consult the MediaTek Security Bulletin for February 2025 for detailed patch information and contact their device manufacturers for firmware updates that incorporate this fix.

Since MediaTek provides chipsets to various OEM manufacturers, the actual firmware update process will depend on your specific device vendor. Contact your access point or router manufacturer for updated firmware containing the MediaTek security patch.

Workarounds

• Reduce wireless transmission power to limit the physical range from which exploitation is possible
• Implement wireless intrusion prevention systems (WIPS) to detect and block malicious wireless traffic
• Consider temporary replacement of affected access points with alternative hardware in high-security environments
• Enable MAC address filtering as an additional layer, though this does not prevent exploitation from authenticated attackers

# Verify affected MediaTek chipset presence (Linux-based devices)
lspci | grep -i mediatek
lsusb | grep -i mediatek
dmesg | grep -i mt76

# Check firmware version for patch status
cat /sys/class/ieee80211/phy*/device/driver/module/version