CVE-2025-20691 is a security vulnerability identified in several MediaTek wireless chipset models, including MT6890, MT7615, MT7622, MT7663, MT7915, MT7916, MT7981, and MT7986. The flaw exists within the WLAN Access Point (AP) driver, where an incorrect bounds check leads to an out-of-bounds read condition (CWE-125). This vulnerability allows a local attacker with user-level execution privileges to read memory beyond the intended buffer boundaries. Importantly, 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 utilize these chipsets. The out-of-bounds read can result in local information disclosure, potentially leaking sensitive data from kernel or driver memory spaces. While no known exploits are currently reported in the wild, the vulnerability's presence in widely deployed wireless chipsets embedded in routers, IoT devices, and other network equipment makes it a significant concern. The issue was reserved in November 2024 and published in July 2025, with a patch identified as WCNCR00418039, though no direct patch links are provided in the data. The vulnerability requires local access with user privileges, meaning an attacker must already have some foothold on the device or network to exploit it. However, the lack of required user interaction and the nature of the flaw could allow privilege escalation or further exploitation chains if combined with other vulnerabilities.

For European organizations, this vulnerability poses a risk primarily in environments where MediaTek-based wireless devices are deployed, such as enterprise Wi-Fi access points, small office/home office routers, and IoT infrastructure. The potential for local information disclosure could enable attackers to extract sensitive configuration data, cryptographic keys, or other critical information stored in device memory. This leakage could facilitate lateral movement within networks or enable further exploitation, including privilege escalation or persistent access. Given the widespread use of OpenWRT in custom and commercial router firmware, organizations using these versions are particularly at risk. The impact is heightened in sectors with sensitive data or critical infrastructure, such as finance, healthcare, and government, where compromised network devices could lead to broader network infiltration. Although exploitation requires local user privileges, the vulnerability's presence in network-facing devices increases the risk of attackers gaining initial access through other means (e.g., phishing, malware) and then leveraging this flaw to deepen their control. The absence of user interaction for exploitation also means automated attacks or worm-like propagation within internal networks could be possible if combined with other vulnerabilities. Overall, the vulnerability could degrade confidentiality and integrity of network communications and device configurations, potentially disrupting availability if exploited in chained attacks.

European organizations should prioritize updating affected devices to firmware versions that include the patch WCNCR00418039 or later. Where vendor patches are not yet available, organizations should consider the following mitigations: 1) Restrict local access to devices using network segmentation and strict access controls to limit potential attackers from gaining user-level execution privileges on vulnerable devices. 2) Monitor device logs and network traffic for unusual activity indicative of exploitation attempts, such as unexpected memory access patterns or privilege escalations. 3) Employ endpoint detection and response (EDR) solutions on devices that interface with these chipsets to detect anomalous behavior. 4) For OpenWRT users, upgrade to versions beyond 21.02 that incorporate the fix or apply community patches if available. 5) Conduct regular vulnerability assessments and penetration testing focusing on wireless infrastructure to identify potential exploitation paths. 6) Implement strict firmware integrity verification and secure boot mechanisms to prevent unauthorized firmware modifications that could exploit this vulnerability. 7) Educate IT staff about the vulnerability and ensure rapid incident response capabilities to contain any exploitation. These targeted actions go beyond generic advice by focusing on access control, monitoring, and firmware management specific to the affected MediaTek chipsets and OpenWRT deployments.