MediaTek, the world’s second-largest supplier of mobile chipsets, has released a security bulletin disclosing multiple vulnerabilities affecting a broad range of its modem platforms. The company urged device manufacturers to expedite deployment of firmware updates, confirming that fixes had already been provided to partners earlier this summer.
The vulnerabilities, which span both modem and firmware components, were discovered by independent security researchers and MediaTek’s internal validation teams. Although no active exploitation has been detected, researchers caution that the flaws expose attack vectors that could be leveraged by sophisticated adversaries if left unpatched.
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High-Severity Modem Flaws Raise Remote Exploitation Concerns
Three of the disclosed flaws carry high-severity ratings under the Common Vulnerability Scoring System (CVSS v3.1). The most serious, identified as CVE-2025-20708, involves an out-of-bounds write in buffer validation logic within the modem. Security experts warn that this flaw allows a remote attacker, operating a rogue base station, to execute code on a targeted device without requiring user interaction.
A related vulnerability, CVE-2025-20703, stems from an out-of-bounds read in the same component. While it does not enable full code execution, the flaw could be exploited to trigger denial-of-service attacks under similar remote conditions. The third, CVE-2025-20704, also arises from a missing bounds check in modem operations. Unlike the first two, exploitation requires limited user interaction but still carries the risk of privilege escalation.
These flaws affect more than 60 modem variants, including chipsets widely used in mid-range and premium smartphones.
Medium-Severity Firmware Bugs Expand Risk Surface
Alongside the modem issues, MediaTek disclosed three medium-severity use-after-free vulnerabilities within different firmware modules. Tracked as CVE-2025-20705, CVE-2025-20706, and CVE-2025-20707, these flaws occur in the monitor_hang, mbrain, and geniezone modules, respectively.
While they require local privileges to exploit, successful attacks could allow malicious applications or compromised processes to escalate rights or execute arbitrary code. The affected devices range across Android 13–16, OpenWRT distributions, and embedded Linux systems, suggesting potential impact beyond consumer smartphones.
Industry Response and Deployment Timeline
MediaTek stated that patches were distributed to original equipment manufacturers (OEMs) in July, giving vendors a two-month lead time before public disclosure. The company emphasized that updated Modem NR and Android BSP versions are essential for mitigating the risks. Final firmware images containing fixes are expected to roll out to consumer devices over the coming weeks.
Security researchers note that, while no exploitation has been observed, the disclosure highlights the expanding attack surface of modern chipsets as they integrate complex networking and task-scheduling functions. For MediaTek, which powers hundreds of millions of devices globally, the timely adoption of the patches will be critical in containing potential threats.