Is CVE-2021-21281 actively exploited?

No active exploitation of CVE-2021-21281 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-21281 be exploited remotely?

Yes. CVE-2021-21281 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-21281?

CVE-2021-21281 has a CVSS score of 9.8 (CRITICAL).

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CRITICAL

CVE-2021-21281

CWE-120Published: 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. 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.

NVD Source

Technical Analysis

CVE-2021-21281 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.