CVE-2025-20714 is a stack overflow vulnerability categorized under CWE-121, discovered in the WLAN Access Point (AP) driver code 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, which leads to an out-of-bounds write on the stack. This memory corruption flaw can be exploited by a local attacker who already possesses System-level privileges to escalate their privileges further, potentially gaining higher control over the device or executing arbitrary code with elevated rights. The vulnerability does not require user interaction, making it easier to exploit in compromised environments. Affected versions include SDK release 7.6.7.2 and earlier, as well as openWRT versions 19.07 and 21.02 for the MT6890 chipset. The CVSS v3.1 base score is 7.8, reflecting high severity due to the combined impact on confidentiality, integrity, and availability, and the relatively low attack complexity and privileges required. No public exploits have been reported yet, but the vulnerability poses a significant risk to devices using these chipsets, especially in embedded wireless infrastructure. The issue is tracked internally by MediaTek as MSV-3902 and patch ID WCNCR00432659, though no direct patch links are provided in the source data.

The vulnerability allows local attackers with existing System privileges to perform out-of-bounds writes on the stack, which can lead to privilege escalation, arbitrary code execution, or system instability. This compromises the confidentiality, integrity, and availability of affected devices. Wireless access points and embedded systems using the vulnerable MediaTek chipsets could be taken over or manipulated, potentially disrupting network operations or enabling further lateral movement within organizational networks. Given the widespread use of MediaTek chipsets in consumer and enterprise wireless devices, the impact could extend to critical infrastructure, IoT deployments, and enterprise networking equipment. Organizations relying on these chipsets may face increased risk of insider threats or post-compromise escalation, undermining trust in network security and potentially leading to data breaches or denial of service conditions.

Organizations should immediately identify devices using the affected MediaTek chipsets and verify firmware or SDK versions. Applying the vendor-released patch identified as WCNCR00432659 is the primary mitigation step once available. Until patches are deployed, restrict local system access to trusted personnel only, enforce strict access controls, and monitor for unusual activity indicative of privilege escalation attempts. Network segmentation can limit the impact of compromised devices. Additionally, updating openWRT installations to versions beyond 21.02 or applying vendor patches is critical. Employ runtime protections such as stack canaries and address space layout randomization (ASLR) where possible to mitigate exploitation. Regularly audit and harden wireless infrastructure configurations to reduce attack surface. Finally, maintain vigilance for any emerging exploit reports and update incident response plans accordingly.