CVE-2025-20714 is a stack overflow vulnerability classified under CWE-121, discovered 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, which allows an out-of-bounds write on the stack. This memory corruption can be exploited to escalate privileges locally, but only if the attacker already has System-level privileges on the device. The vulnerability does not require any user interaction, making it exploitable in automated or scripted attacks once initial access is gained. Affected firmware versions include SDK release 7.6.7.2 and earlier, as well as openWRT 19.07 and 21.02 for the MT6890 chipset. The flaw could allow attackers to execute arbitrary code with elevated privileges, potentially compromising the device's confidentiality, integrity, and availability. No public exploits have been reported yet, and no CVSS score has been assigned, but the vulnerability has been officially published and assigned a patch ID (WCNCR00432659). This issue is particularly critical for embedded devices and wireless access points that use these chipsets, as it could be leveraged to gain deeper control over network infrastructure components.

For European organizations, this vulnerability poses a significant risk to network infrastructure devices such as wireless access points and embedded systems that utilize the affected MediaTek chipsets. Successful exploitation could allow attackers who have already compromised a device at the System privilege level to escalate their privileges further, potentially gaining full control over the device. This can lead to unauthorized configuration changes, interception or manipulation of network traffic, and disruption of wireless services. The impact is heightened in environments where these devices serve as critical network access points or gateways, such as in enterprise networks, public Wi-Fi deployments, and industrial control systems. Given the widespread use of MediaTek chipsets in consumer and enterprise-grade wireless equipment, the vulnerability could affect a broad range of organizations. The lack of user interaction required for exploitation increases the risk of automated attacks once initial access is obtained. Although no known exploits are currently active, the vulnerability's presence in widely deployed firmware versions means that unpatched devices remain at risk.

Organizations should prioritize identifying devices using the affected MediaTek chipsets and verify their firmware versions against the vulnerable releases (SDK 7.6.7.2 and earlier, openWRT 19.07 and 21.02 for MT6890). Immediate steps include applying vendor-provided patches or firmware updates as soon as they become available. In the interim, network segmentation and strict access controls should be enforced to limit the ability of attackers to gain System-level privileges on these devices. Monitoring for unusual activity or privilege escalations on wireless access points and embedded devices is critical. Employing host-based intrusion detection systems (HIDS) and network anomaly detection can help identify exploitation attempts. Additionally, organizations should review and harden device configurations, disable unnecessary services, and restrict administrative access to trusted personnel and networks. Regular vulnerability scanning and asset inventory updates will assist in maintaining awareness of affected devices. Collaboration with vendors and participation in security advisories will ensure timely updates and mitigation guidance.