CVE-2025-20735
📋 TL;DR
This CVE describes a buffer overflow vulnerability in MediaTek's wlan AP driver where improper bounds checking allows out-of-bounds writes. An attacker with local user privileges can exploit this to escalate privileges to kernel level without requiring user interaction. This affects devices using MediaTek Wi-Fi chipsets with vulnerable driver versions.
💻 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
Full system compromise with kernel-level code execution, allowing complete control over the device, data theft, and persistence establishment.
Likely Case
Local privilege escalation from user to root/kernel privileges, enabling installation of malware, data access, and further system manipulation.
If Mitigated
Limited impact with proper privilege separation and kernel hardening, potentially causing system instability or crashes instead of full compromise.
🎯 Exploit Status
Requires local user access; no authentication bypass needed once local access obtained
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply patch ID: WCNCR00435349
Vendor Advisory: https://corp.mediatek.com/product-security-bulletin/November-2025
Restart Required: Yes
Instructions:
1. Check device uses MediaTek Wi-Fi chipset 2. Obtain patch from device manufacturer/OEM 3. Apply driver update 4. Reboot system
🔧 Temporary Workarounds
Restrict local user access
allLimit user accounts and privileges on affected systems
Disable Wi-Fi if not needed
linuxTurn off Wi-Fi functionality to remove attack surface
nmcli radio wifi off
ip link set wlan0 down
🧯 If You Can't Patch
- Implement strict access controls and monitor for privilege escalation attempts
- Isolate affected systems from critical network segments and data
🔍 How to Verify
Check if Vulnerable:
Check driver version and patch status via device manufacturer tools; examine system logs for driver loadingCheck Version:
Manufacturer-specific; typically via Android settings or OEM update toolsVerify Fix Applied:
Verify patch WCNCR00435349 is applied through manufacturer update verification📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Driver crash reports
- Unexpected privilege escalation events
Network Indicators:
- Unusual local network activity from compromised hosts
SIEM Query:
Process monitoring for unexpected privilege changes or driver-related crashes