CVE-2025-20677 is a medium-severity vulnerability identified in several MediaTek Bluetooth chipsets, specifically the MT7902, MT7921, MT7922, MT7925, and MT7927 models. The vulnerability arises from a NULL pointer dereference (CWE-476) within the Bluetooth driver. This flaw can cause an uncaught exception leading to a system crash, effectively resulting in a local denial of service (DoS). Exploitation requires user-level execution privileges but does not require any user interaction, meaning an attacker with local access can trigger the crash without additional input from the user. The affected versions include NB SDK release 3.6 and earlier. The CVSS v3.1 base score is 5.5, reflecting a medium severity level, with the vector indicating local attack vector (AV:L), low attack complexity (AC:L), requiring privileges (PR:L), no user interaction (UI:N), unchanged scope (S:U), no impact on confidentiality or integrity (C:N/I:N), but high impact on availability (A:H). No known exploits are currently reported in the wild, and no patch links were provided, though a patch ID (WCNCR00412256) and issue ID (MSV-3284) are referenced. The vulnerability could be triggered by sending malformed Bluetooth packets or commands that cause the driver to dereference a NULL pointer, crashing the Bluetooth subsystem and potentially affecting device stability or connectivity. This could disrupt critical Bluetooth-dependent services or applications on affected devices.

For European organizations, the impact of this vulnerability could be significant in environments where MediaTek Bluetooth chipsets are widely deployed, such as in laptops, IoT devices, and embedded systems. A local denial of service could disrupt business operations relying on Bluetooth connectivity, including wireless peripherals, data transfer, and device management. In sectors like manufacturing, healthcare, and logistics, where Bluetooth-enabled devices are integral to operations, this could lead to operational downtime and reduced productivity. Although the vulnerability does not allow for privilege escalation or data compromise, the availability impact could be exploited by insiders or malicious software with local access to cause repeated crashes, potentially leading to service interruptions or device reboots. The lack of required user interaction lowers the barrier for exploitation once local access is obtained. Given the medium severity, the threat is moderate but should not be underestimated, especially in critical infrastructure or environments with high Bluetooth device density.

Organizations should prioritize updating affected devices to firmware or driver versions beyond NB SDK release 3.6 where the vulnerability is patched. Since no direct patch links are provided, contacting MediaTek or device vendors for the latest security updates is essential. Network segmentation and strict access controls should be enforced to limit local access to devices with vulnerable Bluetooth chipsets. Endpoint protection solutions should monitor for abnormal Bluetooth driver crashes or repeated system restarts indicative of exploitation attempts. Disabling Bluetooth functionality on devices where it is not required can reduce the attack surface. For devices in sensitive environments, consider deploying host-based intrusion detection systems (HIDS) to detect anomalous behavior related to Bluetooth drivers. Additionally, maintain an inventory of devices using MediaTek chipsets to ensure comprehensive coverage during patch management. Regularly review and apply security advisories from MediaTek and device manufacturers to stay updated on remediation progress.