PatchTheCVECVE-2025-66646: RIOT is an open-source microcontroller operating system, designed to match the requirements of Internet of Thi
CVE-2025-66646 is a high-severity flaw (CVSS 7.5) affecting riot. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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
Why this priority
- High severity
- Public exploit reference
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 7.5 (High) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.7% (top 48%) |
| CISA exploited list | No |
| Weakness | CWE-476 |
| Published | 2025-12-17 |
| Last modified | 2026-10-13 |
Last updated 2026-10-13 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2025-66646?
riot: upgrade to 2025.10. Exact commands for each OS are on this page.
Is CVE-2025-66646 being exploited?
CVE-2025-66646 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2025-66646 affect?
CVE-2025-66646 affects riot. Severity is high (CVSS 7.5). 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 o
How urgent is CVE-2025-66646?
Priority 49/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action
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