CVE-2025-20709 is a classic buffer overflow vulnerability classified under CWE-120 found in the WLAN Access Point (AP) driver of 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 operation. This flaw can be exploited remotely by an attacker within network proximity (adjacent or proximal), without requiring any user interaction or prior authentication, making it highly accessible for exploitation. Successful exploitation leads to escalation of privileges on the affected device, granting the attacker elevated control potentially sufficient to compromise the device’s confidentiality, integrity, and availability. 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 been assigned a CVSS v3.1 base score of 8.8, indicating high severity with attack vector as adjacent network, low attack complexity, no privileges required, and no user interaction needed. Although no exploits have been reported in the wild yet, the vulnerability poses a significant risk due to the widespread use of MediaTek chipsets in consumer and enterprise wireless devices. The issue is tracked under MediaTek’s internal ID MSV-3405 and patch ID WCNCR00415809, though no public patch links are currently available. The vulnerability’s impact includes potential full device compromise, enabling attackers to manipulate network traffic, disrupt communications, or pivot into internal networks. This makes it particularly dangerous in environments relying on wireless infrastructure for critical operations.

For European organizations, the impact of CVE-2025-20709 can be substantial. Many enterprises and service providers deploy wireless access points and embedded devices powered by MediaTek chipsets, especially in SMBs and IoT deployments. Exploitation could lead to unauthorized access to internal networks, data exfiltration, service disruption, and lateral movement within corporate environments. Critical sectors such as finance, healthcare, manufacturing, and government services that depend on wireless connectivity could face operational downtime and data breaches. The vulnerability’s ability to escalate privileges remotely without user interaction increases the risk of automated attacks and worm-like propagation within local networks. Additionally, the lack of authentication requirement means attackers can exploit the flaw from adjacent networks, including public or guest Wi-Fi environments, increasing the attack surface. This could undermine trust in wireless infrastructure and necessitate costly incident response and remediation efforts. The potential for confidentiality, integrity, and availability compromise elevates the threat to a critical level for European organizations.

1. Apply official patches from MediaTek as soon as they become available; monitor vendor advisories and security bulletins for updates. 2. For devices running OpenWrt 19.07 or 21.02 on MT6890 chipsets, upgrade to patched firmware versions or consider temporary device replacement if patches are delayed. 3. Segment wireless networks to isolate vulnerable devices from sensitive internal networks, reducing lateral movement risk. 4. Implement strict access controls and network segmentation to limit proximity-based exploitation, including disabling unnecessary wireless interfaces or restricting access to trusted clients only. 5. Monitor network traffic for unusual patterns or anomalies indicative of exploitation attempts, such as unexpected privilege escalations or buffer overflow signatures. 6. Employ intrusion detection/prevention systems (IDS/IPS) tuned to detect attempts targeting MediaTek WLAN vulnerabilities. 7. Conduct regular vulnerability scans and penetration tests focusing on wireless infrastructure to identify and remediate exposures. 8. Educate IT staff about the vulnerability specifics to ensure rapid response and patch management. 9. Consider deploying network-level mitigations such as MAC filtering, WPA3 encryption, and disabling legacy protocols to reduce attack vectors. 10. Maintain an inventory of all devices using affected MediaTek chipsets to prioritize remediation efforts effectively.