# CVE-2016-7434: Denial of service in n/a

> Remote attackers can crash the NTP server by sending a crafted mrulist query, requiring an upgrade to mitigate.

- **Severity:** High 7.5 (`CVSS:3.1/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:** 13 Jan 2017
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2016-7434, GHSA-qf57-pg9f-mrmv, UBUNTU-CVE-2016-7434

## What is CVE-2016-7434?

CVE-2016-7434 is a high-severity denial of service vulnerability in Ntp Ntp, published on 13 Jan 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The read_mru_list function in NTP before 4.2.8p9 allows remote attackers to cause a denial of service (crash) via a crafted mrulist query.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2016-7434?

It affects 2 products.


Products: Hpe Hpux-Ntp, Ntp Ntp.

## How do I fix CVE-2016-7434?

Upgrade to a fixed version.

## Is CVE-2016-7434 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2016-7434 exists.

Public exploit code:

- NTPD remote DOS exploit and vulnerable container (github_poc): https://github.com/opsxcq/exploit-CVE-2016-7434
- https://github.com/shekkbuilder/CVE-2016-7434 (github_poc): https://github.com/shekkbuilder/CVE-2016-7434
- NTP 4.2.8p8 - Denial of Service (exploitdb)
- cve-2016-7434 (github_poc): https://github.com/cved-sources/cve-2016-7434

## Other vulnerabilities in Ntp Ntp

- [CVE-2018-7170](https://insights.sbomify.com/CVE-2018-7170/): Business logic in n/a (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-7434 and fix it if it is affected.

What it is: CVE-2016-7434 is a high-severity denial of service vulnerability in Ntp Ntp, published on 13 Jan 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2016-7434 exists.

Affected product: Ntp Ntp. 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-2016-7434/ (Markdown: https://insights.sbomify.com/CVE-2016-7434/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-7434
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-7434
- OSV: https://osv.dev/vulnerability/CVE-2016-7434

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-7434/
Summaries are generated and may contain mistakes; the official description above is the record.