CVE-2025-66364 in Exynos 850
Summary
by MITRE • 11/05/2026
Continuously sending control‑plane messages causes the baseband to crashes.
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Analysis
by VulDB Data Team • 11/05/2026
The vulnerability described involves a denial of service condition within the cellular modem's baseband processor, specifically triggered by an excessive volume of control-plane signaling messages. In modern mobile communication architectures, such as those based on 3GPP standards for LTE or 5G NR, the user equipment communicates with the network infrastructure through distinct planes: the data plane carries user traffic while the control plane manages connection setup, mobility, and session management. The baseband processor is responsible for interpreting these signaling protocols, including Radio Resource Control (RRC) messages, which dictate how radio resources are allocated and maintained between the device and the cellular tower. When an attacker or a malfunctioning network element continuously sends malformed or excessively frequent control-plane messages, it overwhelms the processing capabilities of the baseband firmware. This resource exhaustion prevents the processor from handling legitimate traffic or maintaining stable state machines, leading to a system crash or reboot of the modem subsystem.
From a technical perspective, this flaw represents a failure in input validation and rate limiting mechanisms within the protocol stack implementation. The baseband software likely lacks sufficient safeguards against message flooding or does not properly handle edge cases where signaling requests exceed predefined thresholds for processing capacity. This aligns with CWE-400, which covers Uncontrolled Resource Consumption, as well as CWE-20, Improper Input Validation, because the system fails to reject or throttle invalid or excessive inputs before they cause a crash. The vulnerability allows an adversary to disrupt service availability without necessarily needing authentication credentials if the messages are sent over the air interface from a rogue base station or via compromised network elements that can inject signaling traffic directly into the control channel.
The operational impact of this vulnerability is significant, primarily manifesting as a denial of service for the affected device. Users may experience sudden loss of cellular connectivity, inability to make calls or send messages, and frequent reboots of the mobile device if the crash affects critical system components beyond just the modem stack. In enterprise environments where devices are used for mission-critical communications, such instability can lead to productivity losses and security risks associated with unexpected restarts that might interrupt secure sessions or leave temporary gaps in protection mechanisms. Furthermore, repeated crashes could potentially be leveraged as a precursor to more complex attacks by forcing the device into a state where it is vulnerable during reboot sequences or when attempting to re-establish connections under degraded conditions.
Mitigation strategies for this vulnerability require both software-level fixes and network-side defenses. On the device side, vendors must implement robust rate limiting algorithms within the baseband firmware to detect and drop excessive control-plane messages from any single source. Input validation routines should be strengthened to ensure that signaling parameters are checked against expected ranges before processing occurs. Additionally, implementing watchdog timers can help recover gracefully from crashes by resetting only the affected subsystem rather than causing a full device reboot if possible. On the network side, operators should deploy intrusion detection systems capable of identifying anomalous signaling patterns indicative of flooding attacks and block such traffic at the core network level. Regular security updates that patch these specific protocol handling flaws are essential to maintaining the integrity and availability of mobile devices in production environments. This issue also maps to MITRE ATT&CK technique T1498, Network Denial of Service, specifically within the context of wireless communication protocols where resource exhaustion is used to degrade service quality for targeted endpoints.