CVE-2025-66646

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.

Affected products

Riot

Riot-os Riot

< 2025.10

Fix

Available

CVSS 3.1

7.5 HIGH

EPSS

0.6% (45th percentile)

Weakness

CWE-476

NVD status

Analyzed

Published

2025-12-17

No exploit for CVE-2025-66646 has been indexed yet. Our index is built from live traffic and upstream syncs, so this page can only say what it knows — not that no exploit exists.