CVE-2025-20713 is a stack overflow vulnerability classified under CWE-121, found in the WLAN 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 that leads to an out-of-bounds write on the stack. This memory corruption can be exploited by a local attacker who already possesses System privileges to escalate their privileges further, potentially gaining higher-level control or executing arbitrary code with elevated rights. The vulnerability does not require user interaction, making it easier to exploit once initial access is obtained. Affected software versions include SDK release 7.6.7.2 and earlier, as well as openWRT 19.07 and 21.02 for the MT6890 chipset. The CVSS v3.1 base score is 7.8, reflecting high severity due to the impact on confidentiality, integrity, and availability, combined with low attack complexity and limited privileges required. Although no public exploits have been reported, the presence of a patch (WCNCR00432661) indicates vendor acknowledgment and remediation efforts. The vulnerability is significant for embedded wireless devices using these chipsets, especially in environments where local system access might be possible.

This vulnerability allows a local attacker with System privileges to perform a stack overflow via an out-of-bounds write, leading to potential privilege escalation. The impact includes compromise of confidentiality, integrity, and availability of the affected device. Attackers could execute arbitrary code with elevated privileges, manipulate or disrupt wireless access point operations, or gain persistent control over network infrastructure components. This poses a significant risk to organizations relying on MediaTek-based wireless access points, especially in enterprise, industrial, or critical infrastructure environments. The vulnerability could facilitate lateral movement within networks, undermine network security controls, and lead to data breaches or denial of service conditions. Given the widespread use of MediaTek chipsets in consumer and enterprise wireless devices, the scope of impact is broad, affecting both small and large organizations globally.

Organizations should immediately identify devices using the affected MediaTek chipsets and verify firmware versions against the vulnerable SDK and openWRT releases. Applying the official patch WCNCR00432661 as soon as it becomes available is critical. If patching is delayed, restrict local system access to trusted personnel only and monitor for unusual activity indicative of privilege escalation attempts. Network segmentation can limit the ability of attackers to reach vulnerable devices. Employ host-based intrusion detection systems (HIDS) to detect anomalous behavior on devices running affected drivers. Vendors and integrators should prioritize updating firmware images and coordinate with customers for timely deployment. Additionally, conduct regular audits of device configurations and access controls to minimize the risk of initial System-level compromise, which is a prerequisite for exploitation. Finally, maintain up-to-date asset inventories to quickly identify and remediate vulnerable devices.