CVE-2025-20733 is a heap overflow vulnerability classified under CWE-122, affecting the wlan AP driver in multiple MediaTek chipsets (MT6890, MT7615, MT7622, MT7663, MT7915, MT7916, MT7981, MT7986). The root cause is an incorrect bounds check leading to an out-of-bounds write on the heap. This flaw can be exploited by an attacker with local user execution privileges to escalate their privileges to a higher level, potentially root or system level. Notably, exploitation does not require any user interaction, which means that once an attacker has user-level access, they can exploit this vulnerability without further action from the user. The affected software versions include SDK release 7.6.7.2 and earlier, as well as openWRT versions 19.07 and 21.02, which are commonly used in embedded devices and wireless access points. The vulnerability was reserved in November 2024 and published in November 2025, with no CVSS score assigned yet and no known exploits in the wild. The absence of a patch link suggests that remediation may still be pending or distributed through vendor-specific channels. The vulnerability poses a significant risk because it allows privilege escalation on devices that often serve as network infrastructure components, potentially enabling attackers to compromise network integrity and confidentiality. Given the widespread use of MediaTek chipsets in consumer and enterprise wireless devices, this vulnerability could have broad implications if exploited.

For European organizations, the impact of CVE-2025-20733 could be substantial, particularly for those relying on wireless access points and embedded devices powered by the affected MediaTek chipsets. Successful exploitation could allow attackers to escalate privileges locally, potentially gaining administrative control over network devices. This could lead to unauthorized access to sensitive data, manipulation of network traffic, or disruption of network services. Critical infrastructure sectors such as telecommunications, manufacturing, and public services that deploy openWRT-based or MediaTek chipset devices may be at higher risk. The lack of required user interaction facilitates stealthy exploitation, increasing the threat to unattended or remotely accessible devices. Additionally, compromised network devices could serve as footholds for lateral movement within corporate networks, amplifying the risk of broader compromise. The vulnerability could also affect IoT deployments, which are prevalent in smart city and industrial environments across Europe, potentially impacting operational technology systems. Overall, the threat could undermine network security, data confidentiality, and service availability in affected organizations.

To mitigate CVE-2025-20733, European organizations should prioritize the following actions: 1) Monitor MediaTek and openWRT vendor channels for official patches or firmware updates addressing this vulnerability and apply them promptly. 2) Restrict local user access to devices running the affected chipsets to trusted personnel only, minimizing the risk of local exploitation. 3) Implement strict network segmentation to isolate wireless access points and embedded devices, limiting the potential for lateral movement if a device is compromised. 4) Employ host-based intrusion detection systems (HIDS) and endpoint protection solutions capable of detecting anomalous behavior indicative of privilege escalation attempts. 5) Regularly audit device firmware versions and configurations to ensure compliance with security policies and identify outdated or vulnerable devices. 6) Where possible, disable or limit unnecessary services on affected devices to reduce the attack surface. 7) For organizations using openWRT, consider upgrading to versions beyond 21.02 or applying community patches that address this issue. 8) Conduct security awareness training for administrators managing these devices to recognize and respond to potential exploitation attempts. These targeted measures go beyond generic advice by focusing on device-specific controls and operational best practices.