Is CVE-2021-21280 actively exploited?

No active exploitation of CVE-2021-21280 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-21280 be exploited remotely?

Yes. CVE-2021-21280 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-21280?

CVE-2021-21280 has a CVSS score of 9.8 (CRITICAL).

HOME VULNERABILITIESCVE-2021-21280

CRITICAL

CVE-2021-21280

CWE-787Published: June 18, 2021· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-21280 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

From a weakness classification perspective (CWE-787): Out-of-bounds write vulnerabilities can lead to data corruption, crashes, or arbitrary code execution.