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 models from MT2735 up to MT8893. 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 maliciously controlled rogue base station. This flaw enables an attacker to escalate privileges on the modem subsystem without requiring any additional execution privileges, user interaction, or authentication, making it highly exploitable in real-world scenarios. The affected modem firmware versions include LR12A, NR15, NR16, NR17, and NR17R. The vulnerability impacts the confidentiality, integrity, and availability of the modem's operations, potentially allowing attackers to intercept communications, manipulate data, or disrupt service. The CVSS v3.1 base score is 8.1, indicating a high severity with network attack vector, high complexity, no privileges required, no user interaction, and high impact across all security dimensions. While no public exploits have been reported yet, the broad range of affected chipsets and the critical role of modems in mobile communications underscore the urgency of addressing this vulnerability. The issue was reserved in November 2024 and published in November 2025, with MediaTek assigning Patch ID MOLY01672601 and Issue ID MSV-4623 for remediation. The vulnerability is particularly concerning for mobile devices and IoT equipment using these chipsets, as attackers can leverage rogue base stations to compromise devices remotely.

For European organizations, the impact of CVE-2025-20727 is significant, especially for those in telecommunications, critical infrastructure, and enterprises relying heavily on mobile connectivity. The vulnerability allows remote attackers to escalate privileges on devices without user interaction, potentially leading to unauthorized access to sensitive communications, data leakage, or disruption of mobile services. This could affect mobile network operators, enterprises with mobile device fleets, and IoT deployments using MediaTek chipsets. The exploitation could undermine trust in mobile communications, cause service outages, or facilitate further attacks such as espionage or sabotage. Given the widespread use of MediaTek chipsets in consumer and industrial devices across Europe, the vulnerability poses a broad risk. Additionally, the ability to exploit via rogue base stations means attackers could target specific geographic areas or organizations by deploying malicious infrastructure. This threat could also impact national security and emergency services relying on mobile networks. The high CVSS score reflects the critical nature of the potential damage to confidentiality, integrity, and availability.

1. Immediate deployment of vendor-provided patches (Patch ID MOLY01672601) for all affected modem firmware versions is critical to remediate the vulnerability. 2. Mobile device manufacturers and network operators should prioritize firmware updates and coordinate with end-users to ensure timely patching. 3. Implement network-level detection and blocking mechanisms for rogue base stations, including anomaly detection systems and enhanced base station authentication protocols. 4. Employ mobile threat defense solutions that can detect suspicious network behavior indicative of rogue base stations. 5. For enterprise and critical infrastructure, enforce strict mobile device management (MDM) policies to monitor device firmware versions and restrict connections to untrusted networks. 6. Increase user awareness about the risks of connecting to unknown or suspicious cellular networks, although user interaction is not required for exploitation, awareness can aid in detection. 7. Collaborate with telecom regulators and industry groups to enhance base station security standards and rapid incident response capabilities. 8. Conduct regular security audits and penetration testing focusing on mobile network infrastructure and endpoint devices using MediaTek chipsets. 9. Consider network segmentation and isolation of critical systems to limit the impact of compromised mobile devices. 10. Maintain up-to-date threat intelligence feeds to monitor for emerging exploits or attack campaigns leveraging this vulnerability.