CVE-2025-20761 is a vulnerability classified under CWE-754 (Improper Check for Unusual or Exceptional Conditions) affecting a broad range of MediaTek chipsets, including models from MT2735 through MT8893 series. The flaw exists in the modem firmware where error conditions are not correctly handled, leading to a potential system crash. An attacker can exploit this by setting up a rogue base station that a user equipment (UE) device connects to, triggering the improper error handling and causing a denial of service. The attack vector is remote over the cellular network, requiring no user interaction or elevated privileges, making it relatively easy to exploit in targeted scenarios. The vulnerability impacts availability by crashing the modem subsystem, disrupting cellular connectivity and device functionality. MediaTek has assigned Patch ID MOLY01311265 and Issue ID MSV-4655 to address this issue. The CVSS v3.1 score is 6.5 (medium severity), reflecting the attack complexity as low, no privileges required, no user interaction, and impact limited to availability. No known exploits have been reported in the wild as of the publication date. The vulnerability affects a wide range of MediaTek chipsets commonly used in smartphones, IoT devices, and other cellular-enabled hardware.

The primary impact of CVE-2025-20761 is a remote denial of service condition that can disrupt cellular connectivity by crashing the modem subsystem. This can lead to loss of voice, data, and emergency services on affected devices, potentially causing significant operational disruption for individuals and organizations relying on cellular communications. Critical infrastructure, emergency responders, and enterprises using cellular IoT devices could experience outages or degraded service. While the vulnerability does not allow data theft or device takeover, the loss of availability can have serious consequences, especially in environments where cellular connectivity is essential. The ease of exploitation via a rogue base station and lack of required user interaction increase the risk in hostile environments or targeted attacks. The broad range of affected chipsets means many devices globally could be vulnerable, amplifying the potential scale of impact.

Organizations and device manufacturers should prioritize applying the official patch (MOLY01311265) provided by MediaTek as soon as it becomes available. Network operators and security teams should monitor for rogue base stations and employ detection mechanisms such as IMSI catchers or anomaly detection systems to identify suspicious cellular infrastructure. Device firmware and baseband updates should be deployed promptly to end users through secure update channels. For critical deployments, consider implementing network access controls or cellular network whitelisting to reduce exposure to untrusted base stations. Additionally, educating users about the risks of connecting to unknown cellular networks can help mitigate exploitation. Vendors should also review and improve error handling in modem firmware to prevent similar issues in future chipset designs.