CVE-2025-20759 is a medium severity vulnerability classified as CWE-125 (Out-of-bounds Read) affecting a wide range of MediaTek modem chipsets, including MT2735, MT2737, MT6833 series, MT6853 series, MT6873 series, MT6880 series, MT6980 series, MT8673 series, MT8771, MT8791 series, MT8795T, MT8797, MT8798, and MT8893. The flaw arises from a missing bounds check in the modem firmware, allowing an attacker controlling a rogue base station to induce an out-of-bounds read condition remotely. This can cause the modem to crash or become unresponsive, resulting in a denial of service (DoS) condition on the user equipment (UE). Exploitation does not require user interaction or elevated privileges, making it feasible to execute silently once the UE connects to the malicious base station. The affected modem versions are NR15 and NR16, which are commonly integrated into mobile devices, IoT gateways, and embedded systems. The vulnerability impacts availability only, with no direct compromise of confidentiality or integrity. Although no exploits have been reported in the wild, the broad chipset coverage and ease of triggering the flaw pose a tangible risk. The issue was publicly disclosed on December 2, 2025, with MediaTek assigning patch ID MOLY01673760 and issue ID MSV-4650. The CVSS v3.1 vector is AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H, indicating network attack vector, low attack complexity, required privileges, no user interaction, unchanged scope, no confidentiality or integrity impact, and high availability impact. This vulnerability underscores the importance of secure modem firmware development and the risks posed by rogue cellular infrastructure in the threat landscape.

For European organizations, the primary impact of CVE-2025-20759 is the potential for remote denial of service on devices using affected MediaTek modems. This can disrupt critical communications, especially in sectors relying on mobile connectivity such as telecommunications providers, emergency services, transportation, and industrial IoT deployments. The vulnerability could be exploited by adversaries deploying rogue base stations to selectively target devices, causing service outages or degrading network reliability. This risk is heightened in environments with high reliance on cellular connectivity for operational continuity. Although the vulnerability does not expose sensitive data or allow code execution, the loss of availability can have cascading effects on business operations and safety-critical systems. European mobile network operators and device manufacturers integrating these chipsets may face increased support costs and reputational damage if devices become unstable or unusable. Furthermore, the presence of this flaw highlights supply chain risks associated with embedded components in telecommunications infrastructure and consumer devices. Prolonged exploitation could undermine trust in network services and complicate compliance with regulatory requirements for service availability and resilience.

To mitigate CVE-2025-20759, European organizations should take a multi-layered approach: 1) Coordinate with device manufacturers and MediaTek to obtain and deploy firmware patches (MOLY01673760) for affected modem versions NR15 and NR16 as soon as they become available. 2) Implement network monitoring solutions capable of detecting anomalous base station behavior or unauthorized cellular infrastructure, including the use of IMSI catchers or rogue base stations. 3) Employ device-level protections such as baseband firewalls or modem firmware integrity checks where supported. 4) For critical deployments, consider using devices with alternative modem chipsets not affected by this vulnerability until patches are fully deployed. 5) Educate security teams about the risks of rogue base stations and incorporate detection of such threats into incident response plans. 6) Collaborate with mobile network operators to enhance detection and mitigation of rogue base stations within their networks. 7) Regularly audit and update device inventories to identify all assets using vulnerable MediaTek modems to prioritize patching efforts. 8) Engage with supply chain partners to ensure transparency and timely vulnerability disclosures for embedded components. These steps go beyond generic advice by focusing on infrastructure-level detection and supply chain risk management specific to modem vulnerabilities.