CVE-2025-20732 is a stack overflow vulnerability classified under CWE-121, discovered in the WLAN AP driver code of several MediaTek chipsets, including MT6890, MT7615, MT7622, MT7663, MT7915, MT7916, MT7981, and MT7986. The root cause is an incorrect bounds check in the driver, which allows an out-of-bounds write to occur. This memory corruption flaw can be exploited by a local attacker who already possesses System-level privileges on the device, provided that the OceReducedNeighborReport feature is disabled. The vulnerability does not require any user interaction, making it easier to exploit in environments where an attacker has local access. 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 wireless devices. Although no public exploits have been reported, the flaw could enable escalation of privileges, potentially allowing attackers to execute arbitrary code with higher privileges or cause denial of service by corrupting the stack. The absence of a CVSS score necessitates an assessment based on the technical details, which indicate a high-severity risk due to the potential impact on system integrity and the ease of exploitation once local access is obtained. The vulnerability affects a broad range of MediaTek chipsets widely deployed in consumer and enterprise wireless access points, making it a significant concern for network security.

For European organizations, this vulnerability could have serious implications, especially for those relying on wireless infrastructure built on affected MediaTek chipsets. Successful exploitation could allow attackers with local access to escalate privileges, potentially leading to full control over network devices such as routers and access points. This could result in unauthorized network configuration changes, interception or manipulation of network traffic, and disruption of wireless services. Critical infrastructure providers, enterprises with large wireless deployments, and service providers in Europe could face increased risk of targeted attacks or lateral movement within networks. The vulnerability's presence in openWRT versions also raises concerns for organizations using customized or open-source firmware on their devices. Given the widespread use of MediaTek chipsets in consumer and enterprise-grade equipment, the potential attack surface in Europe is substantial. Additionally, the lack of user interaction required for exploitation increases the threat level in environments where attackers have gained some level of system access.

Organizations should immediately identify and inventory devices using the affected MediaTek chipsets and firmware versions, including those running openWRT 19.07 and 21.02 or SDK release 7.6.7.2 and earlier. Applying vendor patches or firmware updates as soon as they become available is critical. In the interim, administrators should verify and, if possible, enable the OceReducedNeighborReport feature to mitigate the risk of exploitation. Network segmentation and strict access controls should be enforced to limit local access to wireless infrastructure devices. Monitoring for unusual privilege escalation attempts and anomalous behavior on network devices can help detect exploitation attempts early. For open-source firmware users, tracking updates from the openWRT project and applying security patches promptly is essential. Additionally, organizations should implement robust endpoint security measures to prevent attackers from obtaining initial System privileges, which are required for exploitation. Regular security audits and penetration testing focusing on wireless infrastructure can help identify and remediate vulnerabilities proactively.