CVE-2025-20709 is a buffer overflow vulnerability classified under CWE-120, found in the WLAN AP driver of several MediaTek chipsets: MT6890, MT7915, MT7916, MT7981, and MT7986. The vulnerability stems from an incorrect bounds check in the driver code, which allows an attacker to perform an out-of-bounds write. This memory corruption flaw can be exploited remotely by an attacker within wireless proximity (adjacent or proximal) to the target device, without requiring any user interaction or prior authentication. The flaw enables escalation of privileges on the affected device, potentially allowing the attacker to execute arbitrary code or disrupt device operation. The affected software versions include SDK release 7.6.7.2 and earlier, as well as OpenWrt versions 19.07 and 21.02 for the MT6890 chipset. The vulnerability has a CVSS v3.1 base score of 8.8, indicating high severity with attack vector as adjacent network, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. No public exploits have been reported yet, but the vulnerability’s nature and impact make it a critical concern for devices using these chipsets in wireless access points or embedded systems. The issue is tracked internally by MediaTek as MSV-3405 and patch ID WCNCR00415809, though no public patch links are currently available.

This vulnerability poses a significant risk to organizations deploying MediaTek-based wireless access points or embedded devices, as it allows remote attackers within wireless range to escalate privileges without authentication or user interaction. Successful exploitation can lead to full compromise of the device, enabling attackers to execute arbitrary code, disrupt network availability, or exfiltrate sensitive data. This can undermine network security, facilitate lateral movement within corporate networks, and potentially impact critical infrastructure relying on these devices. Given the widespread use of MediaTek chipsets in consumer and enterprise wireless equipment, the scope of affected systems is broad. The high CVSS score reflects the potential for severe confidentiality, integrity, and availability impacts, making this vulnerability a critical threat to wireless network security worldwide.

Organizations should monitor MediaTek’s advisories closely and apply official patches or firmware updates as soon as they become available. In the interim, network administrators should implement strict wireless network segmentation to isolate vulnerable devices from sensitive network segments. Employing wireless intrusion detection and prevention systems (WIDS/WIPS) can help detect anomalous activity indicative of exploitation attempts. Disabling unnecessary wireless services or interfaces on affected devices can reduce the attack surface. Additionally, enforcing strong wireless encryption and authentication mechanisms can limit attacker proximity and access. Regularly auditing device firmware versions and configurations will help identify vulnerable devices. Vendors and integrators should prioritize updating SDKs and OpenWrt builds to patched versions. Finally, organizations should prepare incident response plans specific to wireless device compromise scenarios.