CVE-2026-22214 identifies a stack-based buffer overflow vulnerability in the ethos utility of RIOT OS, an open-source operating system designed for Internet of Things (IoT) devices. The flaw exists in the _handle_char() function, which processes incoming serial frame data by appending bytes to a fixed-size stack buffer without verifying that the write index remains within the buffer's bounds. This lack of bounds checking allows an attacker capable of sending crafted serial or TCP-framed input to cause a buffer overflow by writing beyond the allocated stack memory. The overflow results in memory corruption, which can cause the affected application to crash, potentially leading to denial of service. The vulnerability affects all RIOT OS versions up to and including 2026.01-devel-317. Exploitation requires low privileges (PR:L), no authentication (AT:N), and user interaction (UI:A), with network attack vector (AV:N). The CVSS 4.0 base score is 6.8, reflecting medium severity due to the potential impact on availability and the ease of exploitation. No known exploits are currently reported in the wild, and no patches have been linked yet. Given RIOT OS's deployment in resource-constrained IoT environments, this vulnerability could disrupt critical embedded systems if exploited.

For European organizations, the primary impact of CVE-2026-22214 is the risk of denial of service due to application crashes in devices running vulnerable RIOT OS versions. This can affect IoT deployments in industrial automation, smart city infrastructure, healthcare devices, and other embedded systems relying on RIOT OS. Memory corruption might also be leveraged in complex attack chains to escalate privileges or execute arbitrary code, though this requires additional vulnerabilities or conditions. Disruption of IoT devices can lead to operational downtime, safety hazards, and loss of data integrity. Given the increasing reliance on IoT in European critical infrastructure and manufacturing, this vulnerability poses a moderate risk to availability and operational continuity. The absence of known exploits reduces immediate threat but does not eliminate the risk, especially as attackers may develop exploits over time.

Organizations should monitor RIOT OS vendor channels for official patches addressing CVE-2026-22214 and apply them promptly once available. In the interim, implement strict input validation and bounds checking on serial and TCP interfaces to prevent malformed frames from triggering the overflow. Restrict network access to devices running RIOT OS by segmenting IoT networks and applying firewall rules to limit exposure of serial and TCP ports. Employ intrusion detection systems capable of recognizing anomalous or malformed frame data. Conduct thorough testing of IoT devices to identify vulnerable versions and isolate or replace them if patching is not immediately feasible. Additionally, enforce least privilege principles on devices to reduce the impact of potential exploitation. Regularly update device firmware and maintain an inventory of IoT assets to ensure timely vulnerability management.