CVE-2026-107837 in RIOT
Summary
by MITRE • 10/09/2026
RIOT is an open-source microcontroller operating system designed for Internet of Things devices and other embedded systems. In 2026.07 and earlier, _receive() in sys/net/gnrc/network_layer/sixlowpan/gnrc_sixlowpan.c can route an undersized packet into SFF fragment handling after only a minimal payload check. The code then interprets the packet as a sixlowpan_frag_t or larger fragment header without verifying that the packet snip contains the required bytes. A remote attacker can send a malformed 6LoWPAN fragment that causes gnrc_sixlowpan_frag_recv() to read beyond the packet buffer, potentially disclosing memory and crashing the network stack. No fixed repository release is available as of this review.
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Analysis
by VulDB Data Team • 10/09/2026
The RIOT operating system serves as a foundational open-source platform for Internet of Things devices and embedded systems, providing essential networking capabilities including support for IPv6 over Low-Power Wireless Personal Area Networks via 6LoWPAN. Within the network layer implementation located in sys/net/gnrc/network_layer/sixlowpan/gnrc_sixlowpan.c, a critical vulnerability exists in the _receive() function as of version 2026.07 and earlier releases. This flaw stems from an insufficient validation mechanism during packet processing where undersized packets are incorrectly routed into the Single Fragment Header handling logic without adequate verification of payload integrity. The core technical deficiency lies in the failure to verify that the incoming packet snip contains the necessary bytes required for proper 6LoWPAN fragment header interpretation before proceeding with further parsing operations.
When a remote attacker transmits a malformed or undersized 6LoWPAN fragment, the system fails to perform rigorous bounds checking on the packet buffer prior to casting it as a sixlowpan_frag_t structure or larger fragment header. Consequently, the gnrc_sixlowpan_frag_recv() function attempts to access memory locations beyond the allocated boundaries of the received packet buffer. This out-of-bounds read condition allows an attacker to potentially extract sensitive information from adjacent memory regions that were not intended for exposure, leading to unauthorized data disclosure. Furthermore, because embedded systems often operate with limited resources and strict memory constraints, such invalid memory accesses frequently result in immediate crashes or segmentation faults within the network stack, effectively disrupting connectivity and service availability for the affected device.
From a classification perspective, this vulnerability aligns closely with CWE-125 Out-of-bounds Read, as it involves accessing memory beyond the intended buffer boundary due to improper validation of input data length. Additionally, the exploitation vector corresponds to ATT&CK technique T1046 Network Service Discovery or potentially T1078 Valid Accounts if authentication is bypassed through network layer manipulation, though primarily it represents a denial-of-service condition via resource exhaustion caused by stack crashes. The impact extends beyond simple availability loss; successful exploitation could reveal internal state information of the microcontroller which might aid in subsequent attacks against the device firmware or connected services.
Mitigation strategies for this vulnerability are currently limited due to the absence of an official fixed repository release as of the review date. Administrators and developers should prioritize implementing strict input validation checks within custom forks or local patches before deploying affected versions in production environments. Specifically, code modifications must ensure that packet lengths are verified against expected header sizes prior to any structural casting or pointer arithmetic operations involving fragment headers. Network segmentation policies can also help mitigate risk by isolating IoT devices from untrusted networks until a patched version of RIOT is officially released and validated for stability across target hardware platforms.