Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2025-66646

Severity CVSS v4.0:
LOW
Type:
CWE-476 NULL Pointer Dereference
Publication date:
17/12/2025
Last modified:
22/01/2026

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.

Impact

Vector 4.0
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 CVSS v4.0 Severity and Metrics:

Base Score: 1.70 LOW
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

Attack Vector (AV): Network
Attack Complexity (AC): Low
Attack Requirements (AT): Present
Privileges Required (PR): None
User Interaction (UI): None
Confidentiality (VC): None
Integrity (VI): None
Availability (VA): Low
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): None
Exploit Maturity (E): Unreported

Base Score 4.0
1.70
Severity 4.0
LOW
Vector 3.x
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 7.50 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x
7.50
Severity 3.x
HIGH

Vulnerable products and versions

CPE From Up to
cpe:2.3:o:riot-os:riot:*:*:*:*:*:*:*:* 2025.10 (excluding)
cpe:2.3:o:riot-os:riot:2025.10:rc1:*:*:*:*:*:*
cpe:2.3:o:riot-os:riot:2025.10:rc2:*:*:*:*:*:*
cpe:2.3:o:riot-os:riot:2025.10:rc3:*:*:*:*:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools