CVE-2025-20711 is an out-of-bounds write vulnerability classified under CWE-787 found in the wlan AP driver of several MediaTek chipsets: MT6890, MT7916, MT7981, and MT7986. The root cause is an incorrect bounds check in the driver code, which allows an attacker within wireless proximity to write outside the intended memory boundaries. This memory corruption can be exploited to escalate privileges remotely without requiring any authentication or user interaction, making it a highly dangerous flaw. The vulnerability affects SDK release 7.6.7.2 and earlier, including OpenWrt 19.07 and 21.02 builds for MT6890. The flaw can compromise the confidentiality, integrity, and availability of the affected devices, potentially allowing attackers to execute arbitrary code or disrupt device functionality. Although no public exploits have been reported yet, the vulnerability has been assigned a CVSS v3.1 score of 8.8, reflecting its high impact and ease of exploitation. MediaTek has acknowledged the issue with patch ID WCNCR00422399 and issue ID MSV-3748, but no public patch links are currently available. This vulnerability is particularly concerning for environments relying on these chipsets for wireless access points, as attackers only need to be in wireless range to exploit it.

The impact of CVE-2025-20711 is significant for organizations deploying MediaTek MT6890, MT7916, MT7981, and MT7986 chipsets in their wireless infrastructure. Successful exploitation can lead to full compromise of affected devices, including unauthorized access to sensitive data, disruption of network services, and potential pivoting to other network segments. Since the vulnerability requires no authentication or user interaction and can be triggered remotely within wireless range, it increases the attack surface substantially. This can affect enterprises, service providers, and critical infrastructure relying on these chipsets for wireless connectivity. The compromise of access points could lead to interception or manipulation of network traffic, undermining network security and privacy. Additionally, the ability to escalate privileges remotely may allow attackers to install persistent malware or create backdoors, complicating incident response and remediation efforts.

Organizations should immediately inventory their wireless infrastructure to identify devices using the affected MediaTek chipsets and SDK versions. They should monitor MediaTek’s official channels for the release of patches corresponding to patch ID WCNCR00422399 and apply them promptly. Until patches are available, network administrators should implement network segmentation to isolate vulnerable access points and restrict wireless access to trusted clients only. Employing wireless intrusion detection/prevention systems (WIDS/WIPS) can help detect anomalous activities indicative of exploitation attempts. Disabling unnecessary wireless features or reducing wireless signal range may also reduce exposure. Regular firmware updates and validation of vendor-supplied patches are critical. Additionally, organizations should review logs for unusual activity and prepare incident response plans specific to wireless device compromise. Vendors and integrators should verify that future SDK releases address this and similar vulnerabilities with robust bounds checking and secure coding practices.