CVE-2025-20708 is a high-severity vulnerability classified as CWE-787 (Out-of-bounds Write) affecting a broad range of MediaTek modem chipsets, including models MT2735 through MT8893 and their variants. The vulnerability arises from an incorrect bounds check in the modem firmware, which allows an attacker to perform an out-of-bounds write operation. This flaw can be exploited remotely without requiring any user interaction or prior authentication. Specifically, exploitation occurs when a user equipment (UE) device connects to a rogue base station controlled by an attacker. The attacker can leverage this to escalate privileges remotely on the modem, potentially gaining control over modem operations or executing arbitrary code. The vulnerability impacts modem versions NR15, NR16, NR17, and NR17R. The CVSS v3.1 base score is 8.1, indicating a high severity level, with the vector AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H, meaning the attack can be launched remotely over the network, requires high attack complexity, no privileges or user interaction, and results in high impact on confidentiality, integrity, and availability. No known exploits are currently reported in the wild, and no official patch links are provided yet, though a patch ID (MOLY01123853) and issue ID (MSV-4131) are referenced by MediaTek. This vulnerability is critical for devices relying on affected MediaTek modems, as it undermines the trustworthiness of cellular communications and could lead to unauthorized access or disruption of mobile network services.

For European organizations, this vulnerability poses significant risks, especially for enterprises and service providers relying on mobile communications infrastructure or IoT devices using MediaTek modems. Compromise of the modem firmware could lead to interception or manipulation of sensitive communications, unauthorized network access, or disruption of critical services. Industries such as telecommunications, finance, healthcare, and critical infrastructure that depend on secure mobile connectivity could face data breaches, service outages, or espionage. The fact that exploitation requires only connection to a rogue base station means attackers could deploy malicious base stations in public or targeted areas to compromise devices without physical access or user interaction. This elevates the threat in urban and industrial environments where mobile devices are ubiquitous. Additionally, the vulnerability could be leveraged in supply chain attacks or targeted espionage campaigns against high-value targets in Europe. The high confidentiality, integrity, and availability impacts underscore the potential for severe operational and reputational damage.

European organizations should implement a multi-layered mitigation strategy: 1) Prioritize obtaining and deploying firmware updates from device manufacturers and MediaTek as soon as patches become available, referencing the patch ID MOLY01123853. 2) Employ network-level protections to detect and block rogue base stations using advanced radio frequency monitoring and anomaly detection tools. 3) Enforce strict device management policies to restrict use of vulnerable devices in sensitive environments until patched. 4) Collaborate with mobile network operators to enhance detection and mitigation of unauthorized base stations. 5) Conduct regular security assessments and penetration testing focusing on cellular connectivity components. 6) Educate users and administrators about the risks of connecting to untrusted networks and encourage use of VPNs or encrypted communication channels to reduce exposure. 7) For IoT deployments, consider network segmentation and device isolation to limit the impact of compromised modems. 8) Monitor threat intelligence feeds for emerging exploit reports related to this CVE to respond promptly.