CVE-2025-20711 is a security vulnerability identified in the wlan AP driver software of MediaTek chipsets MT6890, MT7916, MT7981, and MT7986. The root cause is an out-of-bounds write triggered by an incorrect bounds check in the driver code, classified under CWE-1287 (Improper Restriction of Operations within the Bounds of a Memory Buffer). This flaw allows a remote attacker located within wireless range (proximal or adjacent) to escalate privileges on the device without requiring any additional execution privileges or user interaction, making exploitation feasible without user involvement. The affected software versions include SDK release 7.6.7.2 and earlier, and OpenWrt versions 19.07 and 21.02 for MT6890-based devices. The vulnerability could lead to corruption of memory structures, potentially enabling attackers to execute arbitrary code or gain elevated privileges on the device, compromising the confidentiality, integrity, and availability of the wireless access point. Although no public exploits are currently known, the vulnerability's nature and ease of exploitation (no user interaction needed) make it a significant risk. The issue was reserved in November 2024 and published in October 2025, with MediaTek assigning the issue ID MSV-3748 and patch ID WCNCR00422399. The lack of a CVSS score requires an independent severity assessment based on the impact and exploitability factors.

For European organizations, this vulnerability poses a substantial risk to wireless network infrastructure security. Exploitation could allow attackers physically near the target (e.g., within Wi-Fi range) to escalate privileges on access points or routers using affected MediaTek chipsets, potentially leading to unauthorized network access, interception of sensitive data, or disruption of network services. This could impact enterprises, public institutions, and critical infrastructure relying on wireless connectivity. The integrity and availability of wireless networks could be compromised, affecting business continuity and data protection compliance under regulations such as GDPR. Additionally, the vulnerability could be leveraged as a foothold for lateral movement within corporate networks. The absence of user interaction requirements lowers the barrier for exploitation, increasing the threat level. Organizations with widespread deployment of affected devices, especially those using OpenWrt-based firmware or SDK versions prior to 7.6.7.2, are at higher risk. The threat is amplified in environments with dense wireless device usage or where physical security controls are limited.

1. Apply official patches from MediaTek as soon as they become available, specifically addressing the WCNCR00422399 patch for the affected chipsets and firmware versions. 2. For devices running OpenWrt 19.07 or 21.02 on MT6890 chipsets, upgrade to patched firmware releases or consider alternative secure firmware if patches are delayed. 3. Implement strict physical security controls to limit attacker proximity to wireless access points, such as securing device locations and reducing wireless signal leakage outside controlled areas. 4. Monitor wireless network devices for unusual privilege escalations or anomalous behavior indicative of exploitation attempts. 5. Employ network segmentation to isolate critical wireless infrastructure from sensitive internal networks, limiting potential lateral movement. 6. Conduct regular security audits and vulnerability assessments focusing on wireless infrastructure components. 7. Educate IT staff on the specific risks associated with MediaTek chipset vulnerabilities and ensure timely response to security advisories. 8. Consider deploying intrusion detection systems capable of detecting abnormal wireless activity or exploitation attempts targeting access points.