Skip to content
Heist/ feed
Back to feed
Low

RIOT-OS has NULL pointer dereference in gnrc_ipv6_ext_frag_reass

Type: advisorySources: OSV

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.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2025-66646
Confirmed fixed CVEs
Not specified
Updated in this feed
8 Nov 2026, 03:20 UTC · Revision 1

Source evidence

RIOT-OS has NULL pointer dereference in gnrc_ipv6_ext_frag_reass

core-osv · Original source

Published 17 Dec 2025, 19:18 UTC

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.

osv:CVE-2025-66646
Complete source record
{
  "id": "614649da853644e0de3c15b3f4d80049ab950e1564e8ec6d183dda9c3f07e818",
  "url": "https://osv.dev/vulnerability/CVE-2025-66646",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "RIOT-OS has NULL pointer dereference in gnrc_ipv6_ext_frag_reass",
    "summary": "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.",
    "evidence": "osv:CVE-2025-66646",
    "products": [],
    "severity": "low",
    "structured": {
      "id": "CVE-2025-66646",
      "aliases": [
        "CVE-2025-66646",
        "GHSA-v8gx-q9m6-5xm9"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "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"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/riot-os/riot",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "d271fc88a4edbaaaea097717aa1f118700cdbb63"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2025.10"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "d271fc88a4edbaaaea097717aa1f118700cdbb63"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "2025.10"
                  }
                ]
              }
            }
          ],
          "versions": [
            "2025.07-devel",
            "2025.04-RC1",
            "2025.04-devel",
            "2025.01-RC1",
            "2025.01-devel",
            "2024.10-RC1",
            "2024.10-devel",
            "2024.07-RC1",
            "2024.04",
            "2024.07-devel",
            "2024.04-RC1",
            "2024.04-devel",
            "2024.01-RC1",
            "2024.01-devel",
            "2023.10-RC1",
            "2023.10-devel",
            "2023.07-RC1",
            "2023.07-devel",
            "2023.04-RC1",
            "2023.04-devel",
            "2023.01-RC1",
            "2023.01-devel",
            "2022.10-RC1",
            "2022.10-devel",
            "2022.07-RC1",
            "2022.07-devel",
            "2022.04-RC1",
            "2022.04-devel",
            "2022.01-RC1",
            "2022.01-devel",
            "2021.10-RC1",
            "2021.10-devel",
            "2021.07-RC1",
            "2021.07-devel",
            "2021.04-RC1",
            "2021.04-devel",
            "2021.01-RC1",
            "2021.01-devel",
            "2020.10-RC1",
            "2020.10-devel",
            "2020.07-RC1",
            "2020.07-devel",
            "2020.04-RC1",
            "2020.04-devel",
            "2020.01-RC1",
            "2020.01-devel",
            "2019.10-RC1",
            "2019.10-devel",
            "2019.07-RC1",
            "2019.07-devel",
            "2019.04-RC1",
            "2019.04-devel",
            "2019.01-RC1",
            "2018.10-devel",
            "2018.07-RC1",
            "2019.01-devel",
            "2018.10-RC1",
            "2018.07-devel",
            "2018.04-RC1",
            "2018.04-devel",
            "2018.01-RC1",
            "2018.01-devel",
            "2017.10-RC1",
            "2017.10-devel",
            "2017.07-RC1",
            "2017.07-devel",
            "2017.04-RC1",
            "2017.04-devel",
            "2017.01-RC1",
            "2017.01-devel",
            "2016.10-RC1",
            "2016.10-devel",
            "2016.07-RC2",
            "2016.07-RC1",
            "2016.04-RC1",
            "2016.07-devel",
            "2016.03-devel",
            "2015.12-RC1",
            "2015.12-devel",
            "2015.09-RC1",
            "2014.12",
            "2014.05",
            "2014.01",
            "2013.08"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-66646.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:53.366806246Z",
      "provider": "osv",
      "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/user-attachments/files/23903992/reproducer_1.zip",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66646.json",
        "https://github.com/RIOT-OS/RIOT/security/advisories/GHSA-v8gx-q9m6-5xm9",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-66646"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-476"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66646.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-66646",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 522154,
  "published_at": "2025-12-17T19:18:08.696+00:00"
}