RIOT-OS up to 2025.9 IPv6 Fragmentation gnrc_ipv6_ext_frag null pointer dereference

CVSS Meta Temp Score
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CTI Interest Score
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6.3$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, was found in RIOT-OS up to 2025.9. This vulnerability affects the function gnrc_ipv6_ext_frag of the component IPv6 Fragmentation Handler. Such manipulation leads to null pointer dereference. This vulnerability is referenced as CVE-2025-66646. It is possible to launch the attack remotely. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in RIOT-OS up to 2025.9 and classified as problematic. Affected by this issue is the function gnrc_ipv6_ext_frag of the component IPv6 Fragmentation Handler. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is handled as CVE-2025-66646 since 12/05/2025. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 2025.10 eliminates this vulnerability. The upgrade is hosted for download at github.com.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: RIOT-OS 2025.10

Timelineinfo

12/05/2025 CVE reserved
12/17/2025 +12 days Advisory disclosed
12/17/2025 +0 days VulDB entry created
01/22/2026 +36 days VulDB entry last update

Sourcesinfo

Advisory: GHSA-v8gx-q9m6-5xm9
Status: Confirmed

CVE: CVE-2025-66646 (🔒)
GCVE (CVE): GCVE-0-2025-66646
GCVE (VulDB): GCVE-100-337010

Entryinfo

Created: 12/17/2025 21:22
Updated: 01/22/2026 18:25
Changes: 12/17/2025 21:22 (70), 12/20/2025 08:39 (1), 01/22/2026 18:25 (11)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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