CVE-2025-20742 is a heap overflow vulnerability classified under CWE-122 found in the WLAN AP driver of several MediaTek chipsets (MT6890, MT7603, MT7615, MT7622, MT7915, MT7916, MT7981, MT7986). The root cause is an incorrect bounds check in the driver code that allows an attacker to perform an out-of-bounds write on the heap memory. This vulnerability can be exploited remotely by an attacker in wireless proximity to the device, without requiring user interaction or additional execution privileges, making it a potent escalation of privilege vector. Successful exploitation can lead to full compromise of the device’s confidentiality, integrity, and availability, potentially allowing the attacker to execute arbitrary code or disrupt wireless services. The affected software versions include SDK release 7.6.7.2 and earlier, and OpenWrt versions 19.07 and 21.02 for MT6890-based devices. Although no public exploits have been reported yet, the high CVSS score (8.0) reflects the significant risk posed by this vulnerability. The issue was publicly disclosed on November 4, 2025, with MediaTek assigning Patch ID WCNCR00432680 and Issue ID MSV-3949. The vulnerability’s exploitation vector is adjacent network access, meaning attackers must be within wireless range but do not need to authenticate or trick users, increasing the attack surface in environments with many wireless devices.

For European organizations, this vulnerability poses a substantial risk to wireless infrastructure security, especially in enterprises, public institutions, and critical infrastructure relying on MediaTek-based wireless access points. Exploitation could allow attackers to escalate privileges remotely, leading to unauthorized access to internal networks, interception or manipulation of sensitive data, and disruption of wireless services. This could result in data breaches, operational downtime, and loss of trust. Given the widespread use of MediaTek chipsets in consumer and enterprise-grade wireless equipment, the attack surface is broad. Organizations in sectors such as finance, healthcare, government, and telecommunications are particularly at risk due to the sensitivity of their data and services. The lack of required user interaction and the proximity-based attack vector make it easier for attackers to exploit in densely populated or public wireless environments common in European urban centers.

European organizations should immediately inventory their wireless infrastructure to identify devices using the affected MediaTek chipsets and software versions. They should apply vendor-provided patches or firmware updates as soon as they become available, specifically those addressing Patch ID WCNCR00432680. Where patches are not yet available, organizations should consider network segmentation to isolate vulnerable wireless devices from critical systems and restrict wireless access to trusted users and devices only. Implementing strong wireless encryption (WPA3 where possible) and disabling unnecessary wireless services can reduce exposure. Monitoring wireless network traffic for unusual activity and deploying intrusion detection systems capable of detecting anomalous behavior at the wireless layer can help identify exploitation attempts. Additionally, organizations should enforce strict physical security controls to limit attacker proximity and conduct regular security assessments of wireless infrastructure. Collaboration with vendors and participation in information sharing groups can provide timely updates on exploit developments and mitigation strategies.