CVE-2025-20756 is a vulnerability identified in multiple MediaTek modem chipsets, including MT2735, MT6833 series, MT6853 series, MT6873 series, MT6880 series, MT8673 series, MT8755, MT8771, MT8791 series, MT8863, MT8873, MT8883, and MT8893. The flaw stems from a logic error within the modem firmware (specifically Modem NR15), which can cause the system to crash when a UE connects to a maliciously controlled rogue base station. This vulnerability does not require user interaction and can be exploited remotely, although it demands low privileges and has a high attack complexity, as indicated by the CVSS vector (AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H). The primary impact is a denial of service condition, where the modem becomes unresponsive or crashes, potentially disrupting mobile connectivity. The vulnerability is tracked under CWE-1287, which relates to logic errors leading to unintended behavior. No patches are linked yet, but MediaTek has reserved the issue and assigned a patch ID (MOLY01673749). There are no known exploits in the wild at this time. The broad range of affected chipsets indicates a widespread potential impact across many mobile devices using MediaTek modems, commonly found in smartphones, IoT devices, and embedded systems. The vulnerability's exploitation vector involves an attacker setting up a rogue base station to which the victim device connects, triggering the crash without additional privileges or user actions.

For European organizations, the impact primarily involves potential disruption of mobile communications due to denial of service on devices using affected MediaTek modems. Telecom operators may experience increased support calls or service degradation if customers' devices crash unexpectedly. Critical infrastructure sectors relying on mobile connectivity for operational continuity, such as emergency services, transportation, and utilities, could face operational challenges. Enterprises with mobile workforces using affected devices might see productivity losses. The lack of confidentiality or integrity impact limits data breach risks, but availability disruption can have cascading effects on business operations and public safety. The requirement for connection to a rogue base station means targeted attacks are possible in localized areas, potentially affecting high-value targets or strategic locations. Given the widespread use of MediaTek chipsets in consumer and industrial devices, the scope of affected systems is significant, increasing the risk of large-scale service interruptions if exploited.

Organizations should prioritize obtaining and applying official patches from MediaTek or device manufacturers as soon as they become available. In the interim, network operators and security teams should implement detection mechanisms for rogue base stations using radio frequency monitoring tools and anomaly detection systems. Mobile device management (MDM) solutions can enforce policies restricting connections to untrusted networks where feasible. Educating users about the risks of connecting to unknown or suspicious cellular networks can reduce exposure. Telecom providers should enhance their network authentication and validation processes to prevent rogue base station attacks. Incident response plans should include procedures for handling sudden mobile connectivity loss. Collaboration with vendors to receive timely vulnerability intelligence and firmware updates is critical. For critical infrastructure, deploying redundant communication channels and failover mechanisms can mitigate availability risks.