CVE-2025-20689 is a security vulnerability identified in several MediaTek wireless chipset models, including MT6890, MT7615, MT7622, MT7663, MT7915, MT7916, MT7981, and MT7986. The flaw exists in the WLAN Access Point (AP) driver component, where an incorrect bounds check leads to an out-of-bounds read condition (classified under CWE-125). This vulnerability allows a local attacker with user-level execution privileges to read memory beyond the intended buffer boundaries. Notably, exploitation does not require user interaction, increasing the risk of automated or stealthy attacks. The affected software versions include SDK release 7.6.7.2 and earlier, as well as openWRT versions 19.07 and 21.02 that incorporate these chipsets. Although no known exploits are currently reported in the wild, the vulnerability could lead to local information disclosure, potentially exposing sensitive data residing in adjacent memory areas. The issue arises from improper validation of input or data structures within the WLAN AP driver, which could be leveraged by an attacker to read kernel or driver memory, undermining confidentiality. Since the vulnerability requires local user privileges, remote exploitation is unlikely without prior access, but the lack of required user interaction means that once local access is obtained, exploitation can be automated or triggered without further user involvement. The vulnerability has been officially published and assigned a CVE identifier but lacks a CVSS score, indicating that detailed impact assessment and severity rating are pending or not yet standardized. MediaTek has acknowledged the issue with an internal patch ID (WCNCR00418048) and issue ID (MSV-3479), suggesting that fixes are either available or forthcoming.

For European organizations, the impact of CVE-2025-20689 depends largely on the deployment of affected MediaTek chipsets within their wireless infrastructure. Many embedded devices, routers, and IoT gateways in enterprise and industrial environments utilize MediaTek chipsets, especially in cost-sensitive or specialized network equipment. An attacker with local user access on such devices could exploit this vulnerability to read sensitive memory contents, potentially exposing credentials, encryption keys, or configuration data. This could facilitate further lateral movement, privilege escalation, or targeted attacks within corporate networks. Given that openWRT versions 19.07 and 21.02 are affected, organizations using these firmware versions on devices with MediaTek chipsets are at risk. The lack of required user interaction increases the risk of automated exploitation once local access is gained. While remote exploitation is not directly feasible, compromised devices or insider threats could leverage this vulnerability to escalate information disclosure. This is particularly concerning for sectors with high security requirements such as finance, healthcare, critical infrastructure, and government agencies across Europe. Additionally, the vulnerability could impact managed service providers and telecom operators deploying MediaTek-based access points or routers, potentially affecting a broad user base. The confidentiality breach could lead to data leaks, regulatory non-compliance (e.g., GDPR), and reputational damage.

To mitigate CVE-2025-20689, European organizations should prioritize the following actions: 1) Identify and inventory all network devices and embedded systems using the affected MediaTek chipsets and firmware versions (SDK 7.6.7.2 and earlier, openWRT 19.07 and 21.02). 2) Apply vendor-supplied patches or firmware updates as soon as they become available from MediaTek or device manufacturers. If official patches are not yet released, consider temporary mitigations such as disabling or restricting local user access to WLAN AP driver components or affected devices. 3) Implement strict access controls and network segmentation to limit local user access to critical network devices, reducing the attack surface. 4) Monitor device logs and network traffic for unusual activity that could indicate exploitation attempts, focusing on local privilege escalation or information disclosure indicators. 5) For openWRT deployments, upgrade to newer, patched versions or consider alternative firmware that addresses this vulnerability. 6) Educate system administrators and security teams about the vulnerability and the importance of restricting local user privileges on network devices. 7) Employ endpoint detection and response (EDR) solutions on devices where feasible to detect anomalous memory access or exploitation behaviors. These targeted steps go beyond generic advice by focusing on inventory, patch management, access control, and monitoring specific to the affected chipsets and firmware versions.