# CVE-2016-6173: Denial of service in n/a

> Remote DNS master servers can cause denial of service in NSD slave servers via zone transfers with unlimited data, leading to disk consumption and crashes.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Feb 2017
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2016-6173, GHSA-h7fr-j2jh-7mww, UBUNTU-CVE-2016-6173

## What is CVE-2016-6173?

CVE-2016-6173 is a high-severity denial of service vulnerability in n/a, published on 9 Feb 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

NSD before 4.1.11 allows remote DNS master servers to cause a denial of service (/tmp disk consumption and slave server crash) via a zone transfer with unlimited data.

Weakness: CWE-399

## Which versions are affected by CVE-2016-6173?

It affects 1 product.


Products: Nlnetlabs Nsd.

## How do I fix CVE-2016-6173?

Upgrade to a fixed version.

## Is CVE-2016-6173 being exploited?

There is no known exploitation of CVE-2016-6173 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2026-12244](https://insights.sbomify.com/CVE-2026-12244/): Heap overflow and crash with crafted SVCB RR (high 8.7)
- [CVE-2026-12245](https://insights.sbomify.com/CVE-2026-12245/): Denial of DNS over TLS service by any DoT client (high 8.7)
- [CVE-2026-18664](https://insights.sbomify.com/CVE-2026-18664/): Wrong interpretation of ACL ranges (high 8.2)
- [CVE-2026-19401](https://insights.sbomify.com/CVE-2026-19401/): Remote UDP DoS by sending multiple DNS Cookie options (high 8.2)
- [CVE-2026-19538](https://insights.sbomify.com/CVE-2026-19538/): Bypass of BLOCKED ACL items on proxy protocol port over TCP or TLS (high 8.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-6173 and fix it if it is affected.

What it is: CVE-2016-6173 is a high-severity denial of service vulnerability in n/a, published on 9 Feb 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2016-6173 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2016-6173/ (Markdown: https://insights.sbomify.com/CVE-2016-6173/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-6173
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-6173
- OSV: https://osv.dev/vulnerability/CVE-2016-6173

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-6173/
Summaries are generated and may contain mistakes; the official description above is the record.