Is CVE-2021-21410 actively exploited?

No active exploitation of CVE-2021-21410 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-21410 be exploited remotely?

Yes. CVE-2021-21410 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-21410?

CVE-2021-21410 has a CVSS score of 9.1 (CRITICAL).

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CRITICAL

CVE-2021-21410

CWE-125Published: June 18, 2021· Updated: Jun 17, 2026

9.1

CVSS v3.1

Official Description

Contiki-NG is an open-source, cross-platform operating system for Next-Generation IoT devices. An out-of-bounds read can be triggered by 6LoWPAN packets sent to devices running Contiki-NG 4.6 and prior. The IPv6 header decompression function (<code>uncompress_hdr_iphc</code>) does not perform proper boundary checks when reading from the packet buffer. Hence, it is possible to construct a compressed 6LoWPAN packet that will read more bytes than what is available from the packet buffer. As of time of publication, there is not a release with a patch available. Users can apply the patch for this vulnerability out-of-band as a workaround.

NVD Source

Technical Analysis

CVE-2021-21410 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), availability disruption (denial of service), with a CVSS base score of 9.1.