# CVE-2016-8858: Denial of service in n/a

> Remote attackers can cause denial of service via memory consumption by sending duplicate KEXINIT requests to OpenSSH servers.

- **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:** 9 Dec 2016
- **Updated:** 29 May 2026
- **Also known as:** DEBIAN-CVE-2016-8858, GHSA-cfx4-r6f2-m2mc, UBUNTU-CVE-2016-8858

## What is CVE-2016-8858?

CVE-2016-8858 is a high-severity denial of service vulnerability in OpenSSH, published on 9 Dec 2016. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The kex_input_kexinit function in kex.c in OpenSSH 6.x and 7.x through 7.3 allows remote attackers to cause a denial of service (memory consumption) by sending many duplicate KEXINIT requests.  NOTE: a third party reports that "OpenSSH upstream does not consider this as a security issue."

Weakness: CWE-399, CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2016-8858?

It affects 1 product.


Products: OpenSSH.

## How do I fix CVE-2016-8858?

No fix published yet.

## Is CVE-2016-8858 being exploited?

There is no known exploitation of CVE-2016-8858 in the wild and no public exploit code.

Public exploit code:

- Proof of concept for CVE-2016-8858 (github_poc): https://github.com/dag-erling/kexkill

## Other vulnerabilities in OpenSSH

- [CVE-2003-0786](https://insights.sbomify.com/CVE-2003-0786/): Auth bypass in n/a (critical 10.0)
- [CVE-2003-0693](https://insights.sbomify.com/CVE-2003-0693/): Memory corruption in n/a (critical 10.0)
- [CVE-2002-0640](https://insights.sbomify.com/CVE-2002-0640/): Memory corruption in n/a (critical 10.0)
- [CVE-2001-0144](https://insights.sbomify.com/CVE-2001-0144/): Integer overflow in n/a (critical 10.0)
- [CVE-2000-0999](https://insights.sbomify.com/CVE-2000-0999/): Memory corruption in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-8858 and fix it if it is affected.

What it is: CVE-2016-8858 is a high-severity denial of service vulnerability in OpenSSH, published on 9 Dec 2016. 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-2016-8858 in the wild and no public exploit code.

Affected product: OpenSSH. 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-2016-8858/ (Markdown: https://insights.sbomify.com/CVE-2016-8858/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-8858
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-8858
- OSV: https://osv.dev/vulnerability/CVE-2016-8858

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-8858/
Summaries are generated and may contain mistakes; the official description above is the record.