CVE-2022-35927 is a medium-severity buffer overflow vulnerability identified in the Contiki-NG operating system, specifically affecting versions prior to 4.7. Contiki-NG is an open-source, cross-platform OS designed for Internet of Things (IoT) devices, widely used in constrained environments such as sensor networks and embedded systems. The vulnerability resides in the implementation of the RPL-Classic routing protocol, which is used for IPv6 routing in low-power and lossy networks. Within this protocol, the DODAG Information Option (DIO) control message can include a prefix information option that contains a length parameter. The flaw arises because the length parameter is not properly validated before being used in the set_ip_from_prefix function, which copies the prefix data into a buffer. This unchecked copying can lead to a classic buffer overflow condition, potentially allowing an attacker to overwrite adjacent memory. Exploitation requires that the vulnerable device receives a maliciously crafted RPL DIO message from an external source. Since these messages are part of the routing protocol, an attacker positioned within network range or able to inject packets into the network could trigger the overflow. The consequences of successful exploitation could include arbitrary code execution, denial of service (device crash or reboot), or corruption of routing tables, undermining network stability and device integrity. There are no known workarounds, and remediation requires upgrading to Contiki-NG version 4.7 or later, where proper input validation has been implemented to prevent the overflow. No exploits have been reported in the wild to date, but the vulnerability's presence in IoT infrastructure poses a latent risk, especially in environments relying on Contiki-NG for critical sensor or control functions.

For European organizations, the impact of this vulnerability is primarily relevant to sectors deploying IoT devices running Contiki-NG, such as smart cities, industrial automation, environmental monitoring, and critical infrastructure management. Exploitation could lead to disruption of sensor networks, loss of data integrity, or denial of service, potentially affecting operational continuity and safety. Given that IoT devices often operate unattended and may have limited security controls, a successful attack could be leveraged as a foothold for lateral movement or to degrade network reliability. The confidentiality impact is moderate since the vulnerability primarily targets memory corruption rather than direct data exfiltration, but integrity and availability impacts are significant due to the possibility of arbitrary code execution or device crashes. The risk is heightened in environments where devices communicate over wireless or mesh networks susceptible to packet injection. European organizations with deployments in smart grids, transportation systems, or healthcare IoT could face operational disruptions and increased maintenance costs. Furthermore, compromised IoT devices could be used as part of botnets or to launch further attacks, amplifying the threat landscape.

1. Immediate upgrade to Contiki-NG version 4.7 or later is essential to eliminate the vulnerability. 2. Implement network segmentation to isolate IoT devices running Contiki-NG from critical enterprise networks, limiting exposure to malicious RPL DIO messages. 3. Deploy intrusion detection systems (IDS) or network monitoring tools capable of identifying anomalous RPL traffic or malformed DIO messages to detect potential exploitation attempts. 4. Restrict physical and network access to IoT devices to trusted entities only, reducing the risk of unauthorized packet injection. 5. Where possible, employ secure routing protocol extensions or cryptographic protections to authenticate RPL control messages, mitigating the risk of spoofed or malicious routing information. 6. Conduct regular firmware audits and vulnerability assessments on IoT deployments to ensure timely patching and detection of compromised devices. 7. Collaborate with IoT device manufacturers and vendors to ensure secure update mechanisms and incident response capabilities are in place.