CVE-2025-20748
📋 TL;DR
This vulnerability in MediaTek wlan AP driver allows local privilege escalation through an out-of-bounds write due to incorrect bounds checking. Attackers with initial System privilege can exploit this without user interaction to gain higher privileges. Devices using affected MediaTek wireless chipsets are vulnerable.
💻 Affected Systems
- MediaTek wlan AP driver
📦 What is this software?
Openwrt by Openwrt
Openwrt by Openwrt
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with root/kernel-level access, allowing installation of persistent malware, data theft, and lateral movement within the network.
Likely Case
Local privilege escalation from System to kernel/root privileges, enabling attackers to bypass security controls and maintain persistence on compromised devices.
If Mitigated
Limited impact if proper privilege separation and driver sandboxing are implemented, though kernel-level access remains possible.
🎯 Exploit Status
Requires initial System privilege access; exploitation involves triggering the out-of-bounds write condition in the wlan driver.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patch ID: WCNCR00432679
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 WCNCR00432679
3. Update device firmware to latest version
4. Reboot device to apply changes
🔧 Temporary Workarounds
Disable vulnerable driver module
linuxTemporarily disable the affected wlan AP driver module to prevent exploitation
rmmod mt_wlan_ap
echo 'blacklist mt_wlan_ap' >> /etc/modprobe.d/blacklist.conf
Restrict driver permissions
linuxSet restrictive permissions on driver module to limit access
chmod 600 /lib/modules/$(uname -r)/kernel/drivers/net/wireless/mt_wlan_ap.ko
🧯 If You Can't Patch
- Implement strict access controls to limit System privilege access
- Monitor for suspicious driver activity and privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check driver version and patch status: dmesg | grep -i 'mt_wlan_ap' and verify patch WCNCR00432679 is not appliedCheck Version:
modinfo mt_wlan_ap | grep versionVerify Fix Applied:
Verify patch application: check system logs for successful driver update and confirm patch WCNCR00432679 is listed in applied patches📡 Detection & Monitoring
Log Indicators:
- Kernel panic or crash logs related to wlan driver
- Unexpected privilege escalation events
- Driver module loading/unloading anomalies
Network Indicators:
- Unusual wireless driver behavior or crashes
- Abnormal system calls to driver functions
SIEM Query:
source="kernel" AND ("mt_wlan_ap" OR "wlan driver") AND ("panic" OR "oops" OR "segfault")