CVE-2025-20716 is an out-of-bounds write vulnerability classified under CWE-787 found in the WLAN Access Point (AP) driver 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 code, which allows writing outside the intended memory buffer. This flaw can be exploited by a local attacker who already possesses System-level privileges to escalate their privileges further, potentially gaining higher-level control over the device. The vulnerability does not require user interaction, increasing its risk in environments where attackers have some level of system access. Affected versions include SDK release 7.6.7.2 and earlier, as well as openWRT versions 19.07 and 21.02 for the MT6890 chipset. The CVSS v3.1 base score is 7.8, reflecting high severity with impacts on confidentiality, integrity, and availability. Although no public exploits have been reported, the vulnerability’s nature suggests that exploitation could lead to significant system compromise, including arbitrary code execution or denial of service. The issue was officially published on October 14, 2025, with MediaTek assigning the patch ID WCNCR00421149 and issue ID MSV-3728. Due to the widespread use of these chipsets in wireless networking equipment, this vulnerability poses a substantial risk to network infrastructure devices.

This vulnerability allows a local attacker with System privileges to perform an out-of-bounds write, which can lead to privilege escalation, arbitrary code execution, or system instability. The impact extends to confidentiality, integrity, and availability of affected devices, potentially allowing attackers to manipulate network traffic, disrupt wireless communications, or gain persistent control over network infrastructure. Organizations relying on MediaTek-based WLAN APs may face increased risk of internal compromise, lateral movement, or disruption of critical network services. The absence of required user interaction and the relatively low complexity of exploitation (given existing System privileges) increase the likelihood of successful attacks in compromised environments. This could affect enterprise networks, ISPs, and service providers using affected hardware, leading to operational downtime, data breaches, or further exploitation within corporate networks.

1. Apply official patches from MediaTek as soon as they become available, specifically addressing SDK releases and openWRT versions mentioned. 2. Restrict local system access to trusted administrators only, minimizing the risk of attackers gaining System privileges. 3. Implement strict access controls and monitoring on devices using affected chipsets to detect anomalous behavior related to WLAN driver operations. 4. Use network segmentation to isolate critical infrastructure and limit the impact of potential compromises. 5. Regularly audit and update firmware and software on networking equipment to ensure vulnerabilities are addressed promptly. 6. Employ host-based intrusion detection systems (HIDS) to monitor for suspicious local privilege escalation attempts. 7. Coordinate with vendors and security teams to validate the integrity of WLAN drivers and firmware images to prevent tampering.