CVE-2025-20748 is a classic buffer overflow vulnerability categorized under CWE-120, found in the WLAN Access Point (AP) driver of several MediaTek chipsets (MT6890, MT7615, MT7622, MT7663, MT7915, MT7916, MT7981, MT7986). The root cause is an incorrect bounds check in the driver code, which allows an out-of-bounds write operation. This flaw can be exploited by a malicious actor who already possesses System-level privileges on the affected device to escalate their privileges further, potentially gaining higher control over the system. The vulnerability does not require user interaction, making it easier to exploit once local access is obtained. Affected software versions include SDK release 7.6.7.2 and earlier, as well as openWRT versions 19.07 and 21.02, which are commonly used in embedded wireless devices. The CVSS v3.1 base score is 6.7, reflecting a medium severity with high impact on confidentiality, integrity, and availability, but limited by the requirement of high privileges for exploitation. No public exploits have been reported yet, but the vulnerability poses a significant risk in environments where attackers can gain local system access. The issue is tracked internally by MediaTek under patch ID WCNCR00432679 and issue ID MSV-3950. The vulnerability could allow attackers to manipulate WLAN driver behavior, potentially leading to system instability, data corruption, or further privilege escalation.

For European organizations, this vulnerability poses a risk primarily in environments where MediaTek chipsets are deployed in wireless networking equipment, such as enterprise access points, routers, or embedded IoT devices running affected SDK or openWRT versions. Successful exploitation could lead to local privilege escalation, enabling attackers to gain full control over affected devices, compromise sensitive data, disrupt network availability, or pivot to other internal systems. This is particularly concerning for critical infrastructure sectors, telecommunications, and enterprises relying on MediaTek-based wireless solutions. The medium severity rating reflects that while remote exploitation is not possible, the prerequisite of System-level access means the threat is more relevant in scenarios involving insider threats, compromised credentials, or chained attacks. The confidentiality, integrity, and availability of network infrastructure could be impacted, potentially leading to data breaches, service outages, or unauthorized network modifications.

1. Apply official patches from MediaTek as soon as they become available, specifically addressing patch ID WCNCR00432679. 2. Upgrade affected devices to SDK versions later than 7.6.7.2 and openWRT versions beyond 21.02 where the vulnerability is fixed. 3. Restrict local system access to trusted administrators only, minimizing the risk of attackers obtaining System privileges. 4. Implement strict access controls and monitoring on devices using affected MediaTek chipsets to detect anomalous driver behavior or privilege escalation attempts. 5. Conduct regular firmware audits and vulnerability assessments on wireless infrastructure to identify outdated or vulnerable components. 6. Employ network segmentation to isolate critical wireless devices, limiting lateral movement opportunities if compromise occurs. 7. Educate IT staff about the risks of local privilege escalation vulnerabilities and the importance of timely patching in embedded systems.