CVE-2025-20733
📋 TL;DR
This CVE describes a heap-based buffer overflow vulnerability in MediaTek's WLAN AP driver. An attacker with local user privileges can exploit this to execute arbitrary code with kernel privileges, potentially gaining full system control. The vulnerability affects devices using MediaTek Wi-Fi chipsets.
💻 Affected Systems
- MediaTek Wi-Fi chipsets with WLAN AP driver
📦 What is this software?
Openwrt by Openwrt
Openwrt by Openwrt
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attacker to install persistent malware, steal sensitive data, or use device as pivot point in network attacks.
Likely Case
Local privilege escalation to kernel mode, allowing attacker to bypass security controls, install rootkits, or access protected system resources.
If Mitigated
Limited impact if proper kernel hardening, exploit mitigations, and least privilege principles are implemented.
🎯 Exploit Status
Requires local access and user privileges. No user interaction needed once attacker has initial foothold.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: WCNCR00441509
Vendor Advisory: https://corp.mediatek.com/product-security-bulletin/November-2025
Restart Required: Yes
Instructions:
1. Check device manufacturer for firmware updates. 2. Apply MediaTek patch WCNCR00441509. 3. Reboot device to load patched driver.
🔧 Temporary Workarounds
Disable Wi-Fi if not needed
linuxTemporarily disable Wi-Fi functionality to remove attack surface
nmcli radio wifi off
ip link set wlan0 down
Restrict local user access
allLimit which users can execute privileged operations on affected systems
🧯 If You Can't Patch
- Implement strict network segmentation to isolate vulnerable devices
- Deploy endpoint detection and response (EDR) solutions to detect exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check driver version: 'modinfo mt_wlan' or 'dmesg | grep -i mediatek' on Linux systemsCheck Version:
cat /sys/module/mt_wlan/version 2>/dev/null || dmesg | grep -i 'mediatek.*wlan'Verify Fix Applied:
Verify patch WCNCR00441509 is applied in system firmware/driver version📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Driver crash messages in dmesg
- Unusual privilege escalation attempts
Network Indicators:
- Unusual local network traffic from device
- Unexpected outbound connections post-exploit
SIEM Query:
source="kernel" AND ("panic" OR "oops") AND "wlan" OR source="auth" AND event="privilege_escalation"