CVE-2025-66646
Vulnerability Scoring
Analysis In Progress
CVE-2025-66646 Vulnerability Analysis & Exploit Details
CVE-2025-66646
Attack Complexity Details
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Attack Complexity:
Attack Complexity Analysis In Progress
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Attack Vector:
Attack Vector Under Analysis
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Privileges Required:
None
No authentication is required for exploitation.
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Scope:
Impact is confined to the initially vulnerable component.
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User Interaction:
None
No user interaction is necessary for exploitation.
CVE-2025-66646 Details
Status: Received on 17 Dec 2025, 20:15 UTC
Published on: 17 Dec 2025, 20:15 UTC
CVSS Release:
CVE-2025-66646 Vulnerability Summary
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.
Assessing the Risk of CVE-2025-66646
Access Complexity Graph
The exploitability of CVE-2025-66646 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
Exploitability Analysis for CVE-2025-66646
No exploitability data is available for CVE-2025-66646.
Understanding AC and PR
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
CVSS Score Breakdown Chart
Above is the CVSS Sub-score Breakdown for CVE-2025-66646, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
CIA Impact Analysis
Below is the Impact Analysis for CVE-2025-66646, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
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Confidentiality:
None
CVE-2025-66646 does not compromise confidentiality.
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Integrity:
None
CVE-2025-66646 does not impact data integrity.
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Availability:
None
CVE-2025-66646 does not affect system availability.
CVE-2025-66646 References
External 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
CWE Common Weakness Enumeration
CWE-476Protect Your Infrastructure against CVE-2025-66646: Combat Critical CVE Threats
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