CVE-2021-21280

Name: CVE-2021-21280
Creator: NVD / NIST
Published: 2021-06-18T21:15:07.75+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 1.06%

Last modified Jun 17, 2026

CVE-2021-21280 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. It is possible to cause an out-of-bounds write in versions of Contiki-NG prior to 4.6 when transmitting a 6LoWPAN packet with a chain of extension headers. EPSS estimates a 1.06% chance of exploitation in the next 30 days.

Description

Contiki-NG is an open-source, cross-platform operating system for internet of things devices. It is possible to cause an out-of-bounds write in versions of Contiki-NG prior to 4.6 when transmitting a 6LoWPAN packet with a chain of extension headers. Unfortunately, the written header is not checked to be within the available space, thereby making it possible to write outside the buffer. 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

1.06%

60.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-787

Affected Software

Vendor	Product	Versions
Contiki-Ng	Contiki-Ng	< 4.6

References

https://github.com/contiki-ng/contiki-ng/pull/1409Patch, Third Party Advisory
https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-r768-hrhf-v592Exploit, Patch, Third Party Advisory
https://github.com/contiki-ng/contiki-ng/pull/1409Patch, Third Party Advisory
https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-r768-hrhf-v592Exploit, Patch, Third Party Advisory

Timeline

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

Frequently Asked Questions

What is CVE-2021-21280?

How severe is CVE-2021-21280?

CVE-2021-21280 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 1.06% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21280?

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-2021-21280?

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

Scan your code now

Source: NVD / NIST