# CVE-2016-7069: Denial of service in dnsdist

> A remote attacker can crash the dnsdist service on 32-bit systems by sending crafted EDNS0 responses when EDNS Client Subnet is enabled.

- **Severity:** Medium 5.9 (`CVSS:3.0/AV:N/AC:H/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:** 11 Sep 2018
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2016-7069, GHSA-v3pf-fvxp-8mjf, UBUNTU-CVE-2016-7069

## What is CVE-2016-7069?

CVE-2016-7069 is a medium-severity denial of service vulnerability in Open-Xchange dnsdist, published on 11 Sep 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue has been found in dnsdist before 1.2.0 in the way EDNS0 OPT records are handled when parsing responses from a backend. When dnsdist is configured to add EDNS Client Subnet to a query, the response may contain an EDNS0 OPT record that has to be removed before forwarding the response to the initial client. On a 32-bit system, the pointer arithmetic used when parsing the received response to remove that record might trigger an undefined behavior leading to a crash.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2016-7069?

It affects 1 product.


Products: Powerdns Dnsdist.

## How do I fix CVE-2016-7069?

Upgrade to a fixed version.

## Is CVE-2016-7069 being exploited?

There is no known exploitation of CVE-2016-7069 in the wild and no public exploit code.

## Other vulnerabilities in Open-Xchange dnsdist

- [CVE-2017-7557](https://insights.sbomify.com/CVE-2017-7557/): Cross-site request forgery in dnsdist (high 8.8)
- [CVE-2026-33593](https://insights.sbomify.com/CVE-2026-33593/): Denial of service via crafted DNSCrypt query (high 7.5)
- [CVE-2026-33602](https://insights.sbomify.com/CVE-2026-33602/): Off-by-one access when processing crafted UDP responses (medium 6.5)
- [CVE-2026-24029](https://insights.sbomify.com/CVE-2026-24029/): DNS over HTTPS ACL bypass (medium 6.5)
- [CVE-2026-27853](https://insights.sbomify.com/CVE-2026-27853/): Out-of-bounds write when rewriting large DNS packets (medium 5.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-7069 and fix it if it is affected.

What it is: CVE-2016-7069 is a medium-severity denial of service vulnerability in Open-Xchange dnsdist, published on 11 Sep 2018. 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-2016-7069 in the wild and no public exploit code.

Affected product: Open-Xchange dnsdist. 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-2016-7069/ (Markdown: https://insights.sbomify.com/CVE-2016-7069/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-7069
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-7069
- OSV: https://osv.dev/vulnerability/CVE-2016-7069

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-7069/
Summaries are generated and may contain mistakes; the official description above is the record.