CVE-2025-66647 RIOT OS has buffer overflow in gnrc_ipv6_ext_frag_reass
Attacker can trigger buffer overflow in IPv6 reassembly to corrupt memory and potentially execute code on IoT devices using RIOT OS.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-66647?
CVE-2025-66647 is a low-severity memory corruption vulnerability in RIOT-OS RIOT, published on 17 Dec 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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 copying the contents of the first fragment (offset=0) into the reassembly buffer, no size check is performed. It is possible to force the creation of a small reassembly buffer by first sending a shorter fragment (also with offset=0). Overflowing the reassembly buffer corrupts the state of other packet buffers which an attacker might be able to used to achieve further memory corruption (potentially resulting in remote code execution). To trigger the vulnerability, the `gnrc_ipv6_ext_frag` module must be included and the attacker must be able to send arbitrary IPv6 packets to the victim. Version 2025.10 fixes the issue.
Weakness: CWE-120
Which versions are affected by CVE-2025-66647?
It affects 1 product.
Products include Riot-Os Riot.
How do I fix CVE-2025-66647?
No fix has been published for CVE-2025-66647 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-66647 being exploited?
There is no known exploitation of CVE-2025-66647 in the wild and no public exploit code.
Other vulnerabilities in RIOT-OS RIOT
Sources
Also known as GHSA-wh3v-q6vr-j79r.