CVE-2021-21281

9.8 criticalEPSS 0.9%

Critical (9.8) in contiki-ng contiki-ng. EPSS 0.9% chance of exploitation in the next 30 days.

Contiki-NG is an open-source, cross-platform operating system for internet of things devices. A buffer overflow vulnerability exists in Contiki-NG versions prior to 4.6. After establishing a TCP socket using the tcp-socket library, it is possible for the remote end to send a packet with a data offset that is unvalidated. The problem has been patched in Contiki-NG 4.6. Users can apply the patch for this vulnerability out-of-band as a workaround.

Severity

CVSS 3.1

9.8 critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.9% chance of exploitation in the next 30 days; higher than 60% of CVEs (scores of 2026-10-31)
CWE: CWE-120
Published: 2021-06-18
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

contiki-ng:contiki-ng

References

https://github.com/contiki-ng/contiki-ng/pull/1366
https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-mc42-fqfr-h9fp
https://github.com/contiki-ng/contiki-ng/pull/1366
https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-mc42-fqfr-h9fp

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