CVE-2025-20728 is a heap overflow vulnerability classified under CWE-122, found in the WLAN STA driver of MediaTek wireless chipsets MT7902, MT7920, MT7921, MT7922, MT7925, and MT7927. The root cause is an incorrect bounds check that leads to an out-of-bounds write on the heap. This vulnerability requires local user execution privileges but does not require any user interaction, making it easier to exploit once local access is obtained. The flaw allows an attacker to perform a local escalation of privilege, potentially enabling them to execute arbitrary code with elevated privileges or cause denial of service by corrupting memory. The affected versions include NB SDK release 3.7 and earlier. The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and limited privileges required. Although no exploits are currently known in the wild, the vulnerability poses a significant risk to devices using these MediaTek chipsets, which are commonly embedded in consumer electronics, IoT devices, and networking equipment. The vendor has assigned patch ID WCNCR00447115 to address the issue.

The vulnerability allows local attackers with user-level execution privileges to escalate their privileges, potentially gaining full control over the affected device. This can lead to unauthorized access to sensitive data, manipulation or deletion of critical information, and disruption of device functionality. Given the widespread use of MediaTek MT79xx chipsets in consumer electronics, IoT devices, and networking hardware, the impact could extend to millions of devices globally. Compromised devices could be used as footholds for lateral movement within networks, increasing the risk of broader organizational compromise. The absence of required user interaction lowers the barrier for exploitation once local access is obtained. This elevates the threat level especially in environments where multiple users share devices or where local access can be gained through other vulnerabilities or physical access. The vulnerability also poses risks to supply chain security and device integrity in critical infrastructure sectors relying on these chipsets.

Organizations should immediately identify devices using the affected MediaTek MT79xx chipsets and verify the SDK versions in use. Applying the vendor-supplied patch WCNCR00447115 or upgrading to a fixed SDK version beyond 3.7 is critical. For devices where patching is not immediately feasible, restricting local user privileges and implementing strict access controls can reduce exploitation risk. Network segmentation and monitoring for unusual local activity can help detect attempts to exploit this vulnerability. Employing endpoint protection solutions capable of detecting anomalous memory corruption behaviors may provide additional defense. Vendors and integrators should validate firmware and driver updates to ensure the vulnerability is fully remediated. Additionally, organizations should review their device inventory and consider replacing legacy hardware that cannot be patched. Security awareness training to minimize local privilege escalation risks and physical security controls to prevent unauthorized local access are also recommended.