CVE-2025-20728 is a heap overflow vulnerability classified under CWE-122, found in the WLAN STA driver of MediaTek's MT7902, MT7920, MT7921, MT7922, MT7925, and MT7927 wireless chipsets. The root cause is an incorrect bounds check that leads to an out-of-bounds write on the heap. This vulnerability can be exploited locally by an attacker who already has user-level execution privileges on the affected system, enabling them to escalate their privileges to higher levels, potentially root or system level. Notably, exploitation does not require any user interaction, increasing the risk of automated or stealthy attacks. The affected software versions include NB SDK release 3.7 and earlier. The CVSS v3.1 base score is 7.8, indicating high severity, with impact metrics showing high confidentiality, integrity, and availability impacts. The attack vector is local (AV:L), requiring low attack complexity (AC:L) and low privileges (PR:L). The vulnerability has been publicly disclosed with no known exploits in the wild yet. MediaTek has assigned a patch ID WCNCR00447115 to address this issue. The vulnerability is significant because wireless chipsets are embedded in a wide range of consumer and enterprise devices, including laptops, IoT devices, and wireless access points, making the attack surface broad. Successful exploitation could allow attackers to bypass security controls, install persistent malware, or disrupt wireless communications.

For European organizations, this vulnerability poses a considerable threat especially in environments where MediaTek MT79xx series chipsets are deployed in wireless networking equipment or IoT devices. The ability to escalate privileges locally means that any compromised user account or malicious insider could gain full control over affected devices, potentially leading to data breaches, lateral movement within networks, and disruption of critical wireless communications. This can impact confidentiality by exposing sensitive data, integrity by allowing unauthorized modifications, and availability by causing device or network outages. Sectors such as manufacturing, healthcare, and critical infrastructure that rely on wireless connectivity and embedded devices are particularly vulnerable. Additionally, the widespread use of MediaTek chipsets in consumer devices means that enterprise networks could be indirectly affected through employee devices, increasing the risk of supply chain or endpoint compromise. The lack of required user interaction lowers the barrier for exploitation, making it easier for attackers to leverage this vulnerability once local access is obtained.

European organizations should immediately identify all devices using MediaTek MT7902, MT7920, MT7921, MT7922, MT7925, and MT7927 chipsets, particularly those running NB SDK release 3.7 or earlier. They should apply the official patch WCNCR00447115 from MediaTek as soon as it becomes available. Until patches are deployed, organizations should enforce strict local user privilege management, limiting user execution privileges and employing application whitelisting to reduce the risk of local exploitation. Network segmentation should be used to isolate vulnerable devices from critical systems. Monitoring for unusual local privilege escalation attempts and anomalous wireless driver behaviors can help detect exploitation attempts. For IoT and embedded devices where patching is delayed or unavailable, consider device replacement or disabling vulnerable wireless interfaces if feasible. Additionally, organizations should review and harden endpoint security policies to prevent unauthorized local code execution. Vendor coordination is essential to ensure timely updates and firmware upgrades are applied across all affected hardware.