RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded devices. A vulnerability was discovered in the IPv6 fragmentation reassembly implementation of RIOT OS v2025.07. When receiving an fragmented IPv6 packet with fragment offset 0 and an empty payload, the payload pointer is set to NULL. However, the implementation still tries to copy the payload into the reassembly buffer, resulting in a NULL pointer dereference which crashes the OS (DoS). To trigger the vulnerability, the `gnrc_ipv6_ext_frag` module must be enabled and the attacker must be able to send arbitrary IPv6 packets to the victim. RIOT OS v2025.10 fixes the issue.
History

Wed, 17 Dec 2025 19:30:00 +0000

Type Values Removed Values Added
Description RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Things (IoT) devices and other embedded devices. A vulnerability was discovered in the IPv6 fragmentation reassembly implementation of RIOT OS v2025.07. When receiving an fragmented IPv6 packet with fragment offset 0 and an empty payload, the payload pointer is set to NULL. However, the implementation still tries to copy the payload into the reassembly buffer, resulting in a NULL pointer dereference which crashes the OS (DoS). To trigger the vulnerability, the `gnrc_ipv6_ext_frag` module must be enabled and the attacker must be able to send arbitrary IPv6 packets to the victim. RIOT OS v2025.10 fixes the issue.
Title RIOT-OS has NULL pointer dereference in gnrc_ipv6_ext_frag_reass
Weaknesses CWE-476
References
Metrics cvssV4_0

{'score': 1.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2025-12-17T20:30:49.970Z

Reserved: 2025-12-05T20:23:19.595Z

Link: CVE-2025-66646

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2025-12-17T20:15:56.170

Modified: 2025-12-17T20:15:56.170

Link: CVE-2025-66646

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.