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7.8

RIOT OS IPv6 fragment handling can overflow memory

CVE-2025-66647 · published 10 months ago
Summary

The RIOT operating system for tiny devices can copy IPv6 data into a buffer without checking its size, which may let a crafted network packet overwrite memory. An attacker who can send IPv6 packets to the device could cause crashes or potentially take control. Update to the version released after July 2025 to fix the problem.

What to do
  • Update riot-os riot to version 2025.10 or later.
Affected software
VendorProductAffected versions
riot-os riot < 2025.10
2025.10
cpe:2.3:o:riot-os:riot:*:*:*:*:*:*:*:*
Original advisory text
RIOT OS has buffer overflow 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 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.
References
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker partial control
Severity
7.8 High
Exploitation
<1% chance of attack within 30 days
Type
CWE-120Classic Buffer Overflow
Timeline
Published17 Dec 2025
Updated3 Nov 2026
First seen7 Mar 2026
Sources
CVE-2025-66647 · NVD
CVE-2025-66647 · OSV
GHSA-wh3v-q6vr-j79r · GHSA
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