CVE-2025-20753 is a vulnerability in MediaTek modem chipsets (including MT2735 through MT8797 series) caused by an uncaught exception within the modem firmware, specifically in versions NR15 and NR16. This uncaught exception can cause the modem system to crash, resulting in a denial of service condition. The vulnerability can be exploited remotely by an attacker who operates a rogue base station; when a user equipment (UE) connects to this malicious base station, the attacker can trigger the exception without requiring any user interaction or additional execution privileges. The vulnerability is classified under CWE-248 (Uncaught Exception), indicating insufficient exception handling in the code. The CVSS 3.1 base score is 5.3 (medium), reflecting network attack vector, high attack complexity, low privileges required, no user interaction, and impact limited to availability (no confidentiality or integrity impact). The affected products span a broad range of MediaTek modem chipsets widely used in mobile devices and IoT equipment. Although no exploits are known in the wild, the potential for remote denial of service poses risks to device availability and network reliability. A patch identified as MOLY01689252 has been released by MediaTek to address this issue. The vulnerability's exploitation does not allow privilege escalation or data compromise but can disrupt communications by crashing the modem firmware.

For European organizations, the primary impact of CVE-2025-20753 is the potential for remote denial of service on devices using affected MediaTek modem chipsets. This can lead to temporary loss of network connectivity, affecting mobile devices, IoT endpoints, and potentially critical infrastructure relying on cellular communications. Telecommunications providers may experience increased support calls and degraded service quality if rogue base stations are deployed by attackers. Enterprises relying on cellular connectivity for operational technology, remote monitoring, or emergency communications could face interruptions. While confidentiality and data integrity are not directly impacted, availability degradation can disrupt business continuity and emergency response capabilities. The wide range of affected chipsets means many consumer and industrial devices across Europe could be vulnerable, especially in sectors with high reliance on cellular networks. The lack of required user interaction and remote exploitability increases the risk of widespread impact if attackers deploy rogue base stations in populated areas or near critical facilities.

To mitigate CVE-2025-20753, European organizations should prioritize applying the vendor-provided patch MOLY01689252 to all affected MediaTek modem firmware versions (NR15, NR16). Device manufacturers and service providers should coordinate firmware updates and ensure timely deployment to end-user devices. Network operators should implement detection and mitigation strategies against rogue base stations, including monitoring for unauthorized base station signals and employing network anomaly detection tools. Enterprises should consider network segmentation and fallback communication methods to maintain availability during potential DoS events. Security teams should educate users about the risks of connecting to unknown cellular networks and encourage the use of trusted networks only. Additionally, device manufacturers should review exception handling in modem firmware to prevent similar uncaught exceptions. Continuous monitoring of threat intelligence feeds for emerging exploits targeting this vulnerability is recommended to respond promptly to any active attacks.