CVE-2025-66646: RIOT-OS has NULL pointer dereference in gnrc_ipv6_ext_frag_reass
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 gnrcipv6extfrag 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 Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2025-66646?
CVE-2025-66646 is classified with a severity level that impacts the reliability and security of RIOT OS applications due to improper handling of IPv6 fragmentation.
How do I fix CVE-2025-66646?
To fix CVE-2025-66646, update RIOT OS to version 2025.10 or later to address the vulnerability in the IPv6 fragmentation reassembly implementation.
What software versions are impacted by CVE-2025-66646?
CVE-2025-66646 affects RIOT OS versions from 2025.07 to 2025.09.
What type of vulnerability is CVE-2025-66646?
CVE-2025-66646 is a fragmentation reassembly vulnerability within the IPv6 handling component of RIOT OS.
Can CVE-2025-66646 lead to remote attacks?
Yes, CVE-2025-66646 can potentially allow remote attackers to exploit the vulnerability through crafted IPv6 packets.