CVE-2025-20727 is a heap buffer overflow vulnerability classified under CWE-787 found in the modem firmware of a wide range of MediaTek chipsets, including but not limited to MT2735, MT6761, MT6762, MT6769, MT6877, MT6895, and many others. The vulnerability arises from an out-of-bounds write condition in the modem's memory management, which can be triggered remotely when a user equipment (UE) connects to a rogue base station controlled by an attacker. This flaw does not require any user interaction or additional execution privileges, making it highly exploitable in scenarios where an attacker can simulate or control a base station. The affected modem firmware versions include LR12A, NR15, NR16, NR17, and NR17R. Successful exploitation can lead to remote escalation of privilege, potentially allowing attackers to execute arbitrary code, compromise the confidentiality and integrity of communications, or disrupt device availability. The CVSS v3.1 base score is 7.5, reflecting high impact on confidentiality, integrity, and availability, with network attack vector, high attack complexity, low privileges required, and no user interaction needed. Although no known exploits have been reported in the wild, the vulnerability's nature and broad chipset impact necessitate urgent attention. The issue is tracked under MediaTek's internal ID MSV-4623 and patch ID MOLY01672601, though no public patch links are currently available. This vulnerability is particularly critical for mobile devices and IoT equipment using these chipsets, as it undermines the trustworthiness of cellular communications and device security.

For European organizations, the impact of CVE-2025-20727 is significant, especially for those relying on mobile communications infrastructure, IoT deployments, and mobile devices powered by MediaTek chipsets. Successful exploitation could lead to unauthorized access to sensitive data, interception or manipulation of communications, and potential disruption of services. Telecommunications providers, mobile network operators, and enterprises with large mobile workforces could face increased risk of targeted attacks leveraging rogue base stations. The vulnerability could also be exploited for espionage or sabotage, given the ability to escalate privileges remotely without user interaction. Critical sectors such as finance, healthcare, and government agencies using affected devices may experience confidentiality breaches or operational disruptions. The widespread use of MediaTek chipsets in affordable smartphones and IoT devices across Europe increases the attack surface, potentially affecting both consumers and enterprise environments. The lack of user interaction requirement and remote exploitation vector heighten the threat level, making mitigation and detection challenging without proper network controls and device updates.

1. Immediate deployment of vendor patches once available is essential; organizations should monitor MediaTek advisories and firmware updates for affected modem versions (LR12A, NR15, NR16, NR17, NR17R). 2. Network operators should implement detection mechanisms for rogue base stations and anomalous signaling patterns to prevent devices from connecting to malicious infrastructure. 3. Employ network-level filtering and anomaly detection systems to identify and block suspicious base station activities. 4. Encourage end-users and enterprise device managers to update device firmware regularly and verify device integrity. 5. For critical deployments, consider using devices with modem chipsets from vendors with robust security track records or additional hardware-based protections. 6. Implement segmentation and least privilege principles in mobile device management to limit potential lateral movement post-exploitation. 7. Collaborate with mobile network providers to enhance base station authentication protocols and strengthen 5G security features where applicable. 8. Conduct regular security assessments and penetration testing focused on cellular network interfaces and device modem firmware. 9. Educate security teams about the risks of rogue base stations and the importance of monitoring cellular network anomalies. 10. Maintain incident response plans that include scenarios involving cellular network-based attacks.