This vulnerability (CVE-2026-20433) is an out-of-bounds write (CWE-787) in the modem of MediaTek chipsets caused by a missing bounds check. It allows remote escalation of privilege when a user equipment (UE) connects to a malicious base station. The attacker does not require additional execution privileges to exploit this issue, but user interaction is required. The vulnerability impacts numerous MediaTek chipset versions. The CVSS v3.1 score is 8.8, indicating high severity with attack vector being adjacent network, low attack complexity, no privileges required, no user interaction, and high impact on confidentiality, integrity, and availability. As of the published date, no patch or official remediation has been confirmed.

Successful exploitation can lead to remote escalation of privilege on affected MediaTek chipsets, potentially compromising confidentiality, integrity, and availability of the device. The attacker must control a rogue base station and the user device must connect to it. No additional execution privileges are needed by the attacker, increasing the risk. However, user interaction is required for exploitation. There are no known exploits in the wild at this time.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no official patch or remediation level is provided, users and administrators should monitor MediaTek advisories for updates. Avoid connecting to untrusted or suspicious base stations to reduce exposure. No additional mitigation instructions are available from the vendor at this time.