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Vulnerabilities

Vulnerability · 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.

Published Dec 17, 2025 · catalog updated Dec 17, 2025 · RIOT-OS RIOT

Last checked Nov 2, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2025-66646. EPSS is 0.68%. Act only if a listed version of RIOT-OS RIOT is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Low1.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.68%
Remediation
Version ranges on file
Affected products
vendor RIOT-OS RIOT < 2025.10

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 module must be enabled and t

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor RIOT-OS RIOT < 2025.10< 2025.10

How to fix CVE-2025-66646

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-66646. EPSS is 0.68%. Act only if a listed version of RIOT-OS RIOT is installed.

Which versions are affected?

Compare what you have installed with RIOT-OS RIOT < 2025.10 < 2025.10. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.68%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Dec 17, 2025 · EUVD

    Detected

    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 imple

  2. Dec 17, 2025 · EUVD

    Updated

    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 imple

Sources

  • CVE.orgVulnerability recordCVE-2025-66646

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-66646

    30-day exploitation probability 0.68%

    first.org
  • EUVDVulnerability recordEUVD-2025-203929

    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 fr

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Nov 2, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 2, 2026
  • CVE.orgNov 2, 2026
  • EUVDNov 1, 2026