Vulnerability Details 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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 31.8%
CVSS Severity
CVSS v3 Score 7.5
References
- https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L411
- https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L420
- https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L490
- https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L532
- https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L534
- https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/network_layer/ipv6/ext/frag/gnrc_ipv6_ext_frag.c#L544
- https://github.com/RIOT-OS/RIOT/blob/eb65305cf9f1b7affb50b17af5c12341b83a8636/sys/net/gnrc/pktbuf_static/gnrc_pktbuf_static.c#L150C1-L150C76
- https://github.com/RIOT-OS/RIOT/releases/tag/2025.10
- https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-v8gx-q9m6-5xm9
- https://github.com/user-attachments/files/23903992/reproducer_1.zip
Products affected by CVE-2025-66646
-
cpe:2.3:o:riot-os:riot:2013.08
-
cpe:2.3:o:riot-os:riot:2014.01
-
cpe:2.3:o:riot-os:riot:2014.05
-
cpe:2.3:o:riot-os:riot:2014.12
-
cpe:2.3:o:riot-os:riot:2015.09
-
cpe:2.3:o:riot-os:riot:2015.12
-
cpe:2.3:o:riot-os:riot:2016.04
-
cpe:2.3:o:riot-os:riot:2016.07
-
cpe:2.3:o:riot-os:riot:2016.10
-
cpe:2.3:o:riot-os:riot:2017.01
-
cpe:2.3:o:riot-os:riot:2017.04
-
cpe:2.3:o:riot-os:riot:2017.07
-
cpe:2.3:o:riot-os:riot:2017.10
-
cpe:2.3:o:riot-os:riot:2018.01
-
cpe:2.3:o:riot-os:riot:2018.04
-
cpe:2.3:o:riot-os:riot:2018.07
-
cpe:2.3:o:riot-os:riot:2018.10
-
cpe:2.3:o:riot-os:riot:2018.10.1
-
cpe:2.3:o:riot-os:riot:2019.01
-
cpe:2.3:o:riot-os:riot:2019.04
-
cpe:2.3:o:riot-os:riot:2019.07
-
cpe:2.3:o:riot-os:riot:2019.10
-
cpe:2.3:o:riot-os:riot:2020.01
-
cpe:2.3:o:riot-os:riot:2020.01.1
-
cpe:2.3:o:riot-os:riot:2020.04
-
cpe:2.3:o:riot-os:riot:2021.01
-
cpe:2.3:o:riot-os:riot:2021.04
-
cpe:2.3:o:riot-os:riot:2021.07
-
cpe:2.3:o:riot-os:riot:2021.10
-
cpe:2.3:o:riot-os:riot:2022.01
-
cpe:2.3:o:riot-os:riot:2022.04
-
cpe:2.3:o:riot-os:riot:2022.07
-
cpe:2.3:o:riot-os:riot:2022.10
-
cpe:2.3:o:riot-os:riot:2023.01
-
cpe:2.3:o:riot-os:riot:2023.04
-
cpe:2.3:o:riot-os:riot:2023.07
-
cpe:2.3:o:riot-os:riot:2023.10
-
cpe:2.3:o:riot-os:riot:2024.01
-
cpe:2.3:o:riot-os:riot:2024.04
-
cpe:2.3:o:riot-os:riot:2024.07
-
cpe:2.3:o:riot-os:riot:2024.10
-
cpe:2.3:o:riot-os:riot:2025.01
-
cpe:2.3:o:riot-os:riot:2025.04
-
cpe:2.3:o:riot-os:riot:2025.07
-
cpe:2.3:o:riot-os:riot:2025.10