CVE-2025-20719 is a stack overflow vulnerability categorized under CWE-121, found in the WLAN Access Point (AP) driver of multiple MediaTek chipsets (MT6890, MT7603, MT7615, MT7622, MT7915, MT7916, MT7981, 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 remotely by an attacker in proximity (adjacent network attacker) without requiring user interaction or additional execution privileges. The vulnerability allows escalation of privilege on the affected device, potentially enabling the attacker to execute arbitrary code or disrupt device operation. The affected software versions include SDK release 7.6.7.2 and earlier, as well as OpenWrt 19.07 and 21.02 for MT6890 chipset devices. Although no public exploits are known at this time, the vulnerability's nature and ease of exploitation make it a significant risk. The issue was reserved in November 2024 and published in October 2025, with MediaTek identified as the assigner. No CVSS score has been assigned yet, and no official patch links are provided, but the patch ID is WCNCR00418955. This vulnerability is particularly relevant for embedded devices and wireless access points using these chipsets, which are common in consumer and enterprise networking equipment.

For European organizations, this vulnerability poses a significant risk to the security and integrity of wireless networking infrastructure that relies on MediaTek chipsets. Exploitation could allow attackers within wireless range to escalate privileges on access points or embedded devices, potentially leading to unauthorized network access, interception of sensitive data, or disruption of network services. This could compromise confidentiality, integrity, and availability of critical network resources. Given the widespread use of MediaTek chipsets in consumer routers, IoT devices, and some enterprise-grade wireless equipment, organizations with such hardware in their network perimeter or internal infrastructure could face increased risk of lateral movement or persistent compromise. The lack of required user interaction and the ability to exploit remotely from adjacent networks increase the threat level. Additionally, compromised devices could be leveraged as footholds for further attacks or as part of botnets, amplifying the impact on organizational cybersecurity posture.

Organizations should immediately inventory their network infrastructure to identify devices using the affected MediaTek chipsets and software versions (SDK release 7.6.7.2 and earlier, OpenWrt 19.07 and 21.02 for MT6890). Until patches are available, network segmentation should be enforced to limit access to vulnerable devices, especially restricting wireless access to trusted users and devices only. Deploying wireless intrusion detection/prevention systems (WIDS/WIPS) can help detect anomalous activity indicative of exploitation attempts. Firmware updates from device vendors or MediaTek should be applied promptly once released. For devices running OpenWrt, upgrading to versions beyond 21.02 or applying vendor patches is critical. Network administrators should also disable unnecessary wireless services or features that expose the vulnerable driver if possible. Monitoring logs for unusual privilege escalation attempts and conducting regular vulnerability scans targeting MediaTek devices can help detect exploitation. Finally, organizations should engage with vendors to confirm patch availability and timelines and consider replacing legacy hardware that cannot be updated.