CVE-2025-20647 is a vulnerability identified in multiple MediaTek modem chipsets, including but not limited to MT2735, MT6739, MT6761, MT6765, MT6771, MT6785, MT6885, MT6895, MT6980, MT8675, MT8788, and others, spanning a broad range of mobile SoCs. The root cause is a NULL pointer dereference (CWE-476) resulting from a missing bounds check in the modem firmware, specifically affecting modem versions NR12A, NR13, NR15, and NR16. When a user equipment (UE) connects to a rogue base station controlled by an attacker, the modem processes malformed or unexpected data that triggers the NULL pointer dereference, causing the modem system to crash. This leads to a denial of service condition, disrupting mobile connectivity and potentially requiring a device reboot or manual intervention to restore service. The vulnerability does not require any user interaction or elevated privileges, making it remotely exploitable by an attacker capable of setting up a rogue base station within radio range of the target device. The CVSS v3.1 score is 6.5 (medium severity), reflecting the attack vector as adjacent network (the radio interface), low attack complexity, no privileges required, no user interaction, unchanged scope, no impact on confidentiality or integrity, but high impact on availability. Although no public exploits are known, the widespread use of affected MediaTek chipsets in consumer and enterprise mobile devices increases the risk profile. The vendor has assigned patch IDs MOLY00791311 and MOLY01067019 to address the issue, underscoring the importance of firmware updates to remediate the vulnerability.

For European organizations, the primary impact of CVE-2025-20647 is the potential for remote denial of service on mobile devices and embedded systems using affected MediaTek modems. This can disrupt critical communications, especially for sectors relying heavily on mobile connectivity such as telecommunications providers, emergency services, transportation, and IoT deployments. The vulnerability could be exploited by attackers deploying rogue base stations in public or strategic locations to cause widespread service outages or targeted disruptions. Although confidentiality and integrity are not directly affected, the loss of availability can degrade operational capabilities and customer trust. Enterprises with mobile workforce devices or embedded systems using these chipsets may experience intermittent connectivity failures, impacting productivity and service delivery. The lack of user interaction requirement and low complexity of exploitation increase the threat level in environments where physical proximity to targets is feasible. Additionally, mobile network operators may face increased support costs and reputational damage if large-scale outages occur due to this vulnerability.

To mitigate CVE-2025-20647, European organizations should prioritize the following actions: 1) Identify all devices and embedded systems using affected MediaTek modem chipsets and verify their firmware versions against vendor advisories. 2) Apply the official patches MOLY00791311 and MOLY01067019 as soon as they become available from device manufacturers or MediaTek to address the NULL pointer dereference. 3) Implement network monitoring to detect and alert on the presence of rogue base stations or suspicious radio signals within organizational premises, leveraging mobile threat defense solutions where applicable. 4) Educate mobile users and IT staff about the risks of connecting to untrusted networks and encourage the use of VPNs and secure communication channels. 5) Collaborate with mobile network operators to report and mitigate rogue base station activities in critical areas. 6) For IoT deployments, consider network segmentation and fallback connectivity options to maintain availability during potential modem failures. 7) Maintain an incident response plan that includes procedures for handling mobile device outages caused by modem crashes. These steps go beyond generic patching by incorporating proactive detection and response measures tailored to the unique attack vector of this vulnerability.