CVE-2021-21281

Name: CVE-2021-21281
Creator: NVD / NIST
Published: 2021-06-18T21:15:07.85+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 0.92%

Last modified Jun 17, 2026

CVE-2021-21281 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 0.92% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

0.92%

55.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-120

Affected Software

Vendor	Product	Versions
Contiki-Ng	Contiki-Ng	< 4.6

References

https://github.com/contiki-ng/contiki-ng/pull/1366Patch, Third Party Advisory
https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-mc42-fqfr-h9fpPatch, Third Party Advisory
https://github.com/contiki-ng/contiki-ng/pull/1366Patch, Third Party Advisory
https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-mc42-fqfr-h9fpPatch, Third Party Advisory

Timeline

Published: Jun 18, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-21281?

How severe is CVE-2021-21281?

CVE-2021-21281 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.92% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21281?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-21281?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST