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Vulnerability record · CVE-2021-21280 · published 18 June 2021

CVE-2021-21280: Contiki-ng out-of-bounds write vulnerability

Contiki Ng · Contiki Ng

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.

9.8 CVSS 3.1 Critical EPSS 1.1% · top 36.7% CWE-787 · Out-of-bounds write
9.8CVSS 3.1 base score, v2 7.5
1.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 2 tagged exploit
17 Jun 2026Last modified by NVD

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.

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.

References

LinkTags
https://github.com/contiki-ng/contiki-ng/pull/1409 PatchThird Party Advisory
https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-r768-hrhf-v592 ExploitPatchThird Party Advisory
https://github.com/contiki-ng/contiki-ng/pull/1409 PatchThird Party Advisory
https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-r768-hrhf-v592 ExploitPatchThird 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-2021-21280), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.