CVE-2021-21410: Contiki-NG

Critical severity, CVSS 9.1. EPSS: 1.2% chance of exploitation in the next 30 days.

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.

Affected products

• Contiki-NG Contiki-NG: up to and including 4.6

Published 2021-06-18. Last modified 2026-06-17.