CVE-2025-20646 is a critical security vulnerability identified in the WLAN Access Point firmware of several MediaTek chipsets, including MT6890, MT7915, MT7916, MT7981, and MT7986. The root cause is an out-of-bounds write (CWE-787) due to improper input validation within the firmware, which can be triggered remotely without any authentication or user interaction. This flaw allows an attacker to perform remote escalation of privilege, potentially gaining control over the device's firmware execution environment. The vulnerability affects SDK releases 7.6.7.2 and earlier, indicating that devices running these versions are at risk. The CVSS v3.1 base score is 9.8, reflecting the vulnerability's critical nature with network attack vector, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. Although no known exploits have been reported in the wild, the severity and ease of exploitation make it a high-priority issue. The vulnerability could allow attackers to execute arbitrary code, disrupt device operation, or manipulate sensitive data handled by the WLAN AP firmware. MediaTek has assigned a patch ID (WCNCR00389074) and issue ID (MSV-1803) for remediation, though no direct patch links are provided yet. This vulnerability is significant given the widespread use of MediaTek chipsets in consumer and enterprise wireless access points globally.

The impact of CVE-2025-20646 is severe for organizations relying on MediaTek-based wireless access points. Successful exploitation can lead to complete compromise of affected devices, allowing attackers to escalate privileges remotely and execute arbitrary code within the WLAN AP firmware. This could result in unauthorized access to network traffic, interception or manipulation of sensitive data, disruption of wireless network availability, and potential lateral movement within corporate networks. The vulnerability's exploitation does not require user interaction or prior authentication, increasing the risk of automated or worm-like attacks. Enterprises, service providers, and critical infrastructure operators using vulnerable MediaTek chipsets may face significant operational disruptions, data breaches, and loss of trust. The broad impact on confidentiality, integrity, and availability underscores the critical need for timely remediation. Additionally, compromised access points could serve as footholds for further attacks against internal networks.

To mitigate CVE-2025-20646, organizations should: 1) Immediately identify and inventory all devices using affected MediaTek chipsets (MT6890, MT7915, MT7916, MT7981, MT7986) running SDK release 7.6.7.2 or earlier. 2) Apply vendor-provided patches as soon as they become available, referencing patch ID WCNCR00389074 and issue ID MSV-1803. 3) Until patches are deployed, restrict network exposure of vulnerable devices by implementing network segmentation and firewall rules to limit access to WLAN AP management interfaces. 4) Monitor network traffic for unusual activity indicative of exploitation attempts, including unexpected firmware behavior or privilege escalations. 5) Employ intrusion detection/prevention systems (IDS/IPS) tuned to detect anomalous packets targeting WLAN AP firmware vulnerabilities. 6) Consider temporary disabling or replacing vulnerable devices in high-security environments if patching is delayed. 7) Maintain up-to-date asset management and vulnerability scanning to detect similar firmware issues proactively. 8) Coordinate with MediaTek and device vendors for timely updates and security advisories.