Vulnerability record · CVE-2021-21281 · published 18 June 2021

CVE-2021-21281: Contiki-ng classic buffer overflow vulnerability

Contiki Ng · Contiki Ng

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.

9.8 CVSS 3.1 Critical EPSS 0.92% · top 41.3% CWE-120 · Classic buffer overflow

9.8CVSS 3.1 base score, v2 7.5

0.92%EPSS exploitation probability, 30 days

NoNot in CISA KEV

1Affected product versions listed by NVD

4References

17 Jun 2026Last modified by NVD

Description

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Contiki Ng Contiki Ng

References

Link	Tags
https://github.com/contiki-ng/contiki-ng/pull/1366	PatchThird Party Advisory
https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-mc42-fqfr-h9fp	PatchThird Party Advisory
https://github.com/contiki-ng/contiki-ng/pull/1366	PatchThird Party Advisory
https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-mc42-fqfr-h9fp	PatchThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-21281), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.