CVE-2025-20674: OpenWrt Privilege Escalation Vulnerability

CVE-2025-20674 Overview

CVE-2025-20674 is a critical vulnerability affecting the WLAN Access Point (AP) driver in multiple MediaTek chipsets and OpenWrt firmware. The vulnerability exists due to a missing permission check in the wireless driver, allowing attackers to inject arbitrary network packets. This flaw enables remote privilege escalation without requiring any user interaction or additional execution privileges.

Critical Impact

Remote attackers can exploit this vulnerability to inject arbitrary packets into the wireless network, potentially leading to complete system compromise through privilege escalation with no user interaction required.

Affected Products

• MediaTek MT7915, MT7916, MT7981, MT7986, MT7990, MT7992, MT7993 (Wi-Fi Chipsets)
• MediaTek MT6890, MT6990 (Mobile Chipsets)
• MediaTek Software Development Kit
• OpenWrt 19.07.0, 21.02.0, 23.05

Discovery Timeline

• 2025-06-02 - CVE-2025-20674 published to NVD
• 2025-07-18 - Last updated in NVD database

Technical Details for CVE-2025-20674

Vulnerability Analysis

This vulnerability falls under CWE-863 (Incorrect Authorization), where the WLAN AP driver fails to properly verify permissions before processing network packet operations. The missing authorization check allows unauthenticated remote attackers to inject crafted packets directly into the wireless network traffic flow. Due to the network-accessible attack vector with low complexity requirements, exploitation can occur without authentication, privileges, or user interaction. Successful exploitation grants attackers elevated privileges on the affected system, enabling full compromise of confidentiality, integrity, and availability.

Root Cause

The root cause is a missing permission check within the WLAN AP driver's packet handling mechanism. The driver accepts and processes network packets without validating whether the source has appropriate authorization to perform such operations. This architectural flaw in the access control logic allows any network-connected attacker to interact with privileged driver functionality.

Attack Vector

The vulnerability is exploitable remotely over the network. An attacker within wireless range or with network access to the affected device can send specially crafted packets that bypass the authorization mechanism. The attack requires:

1. Network connectivity to the target device (wireless or through routing)
2. Crafted packets designed to exploit the missing permission check
3. No authentication credentials or user interaction

The driver processes these malicious packets with elevated privileges, enabling the attacker to escalate their access and potentially gain full control over the affected device.

Detection Methods for CVE-2025-20674

Indicators of Compromise

• Unexpected or anomalous wireless traffic patterns originating from unauthorized sources
• Unusual packet injection activity in wireless network logs
• Unauthorized privilege escalation events on affected MediaTek-based networking devices
• Unexpected driver behavior or crashes in the WLAN AP subsystem

Detection Strategies

• Monitor wireless network traffic for packets with invalid or spoofed source attributes
• Implement intrusion detection rules to identify packet injection attack patterns
• Enable verbose logging on affected OpenWrt and MediaTek-based devices to capture authorization failures
• Deploy network monitoring solutions capable of detecting anomalous wireless protocol behavior

Monitoring Recommendations

• Continuously monitor system logs on devices running affected MediaTek chipsets for privilege escalation indicators
• Implement real-time alerting for unauthorized access attempts to wireless driver interfaces
• Track firmware versions across all affected devices to ensure patch compliance
• Establish baseline wireless traffic patterns to detect injection anomalies

How to Mitigate CVE-2025-20674

Immediate Actions Required

• Apply the security patch referenced by Patch ID: WCNCR00413202 from MediaTek
• Update OpenWrt firmware to the latest patched version if running 19.07.0, 21.02.0, or 23.05
• Review network segmentation to limit exposure of affected wireless devices
• Implement additional network-level access controls pending full remediation

Patch Information

MediaTek has released a security patch addressing this vulnerability. The fix is tracked as Patch ID: WCNCR00413202 and Issue ID: MSV-3303. Detailed patch information is available in the MediaTek Security Bulletin - June 2025. Device manufacturers and OpenWrt users should obtain and apply the updated driver packages from their respective vendors.

Workarounds

• Restrict network access to affected devices using firewall rules and VLAN segmentation
• Disable wireless AP functionality on non-essential devices until patches can be applied
• Implement MAC address filtering as an additional layer of access control (note: not a complete mitigation)
• Monitor wireless interfaces for suspicious activity and disconnect compromised devices immediately

# Example: Restrict wireless interface access via iptables on OpenWrt
iptables -A INPUT -i wlan0 -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -i wlan0 -j DROP

# Example: Disable wireless AP interface temporarily
uci set wireless.@wifi-iface[0].disabled='1'
uci commit wireless
wifi reload