# CVE-2018-16860: Auth bypass in samba

> A man-in-the-middle attacker can intercept KDC requests in Samba AD DC mode to impersonate any user and obtain their authentication tickets.

- **Severity:** High 7.5 (`CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 31 Jul 2019
- **Updated:** 5 Aug 2024
- **Also known as:** ALPINE-CVE-2018-16860, CLEANSTART-2024-BH94102, DEBIAN-CVE-2018-16860, DLA-1788-1, DSA-4443-1, ECHO-9cf7-2c5d-dcf9, GHSA-282x-mj8h-7q8w, UBUNTU-CVE-2018-16860, USN-3976-1, USN-3976-2

## What is CVE-2018-16860?

CVE-2018-16860 is a high-severity authentication bypass vulnerability in Samba Samba, published on 31 Jul 2019. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A flaw was found in samba's Heimdal KDC implementation, versions 4.8.x up to, excluding 4.8.12, 4.9.x up to, excluding 4.9.8 and 4.10.x up to, excluding 4.10.3, when used in AD DC mode. A man in the middle attacker could use this flaw to intercept the request to the KDC and replace the user name (principal) in the request with any desired user name (principal) that exists in the KDC effectively obtaining a ticket for that principal.

Weakness: CWE-358 (Improperly Implemented Security Check for Standard)

## Which versions are affected by CVE-2018-16860?

It affects 2 products.


Products: Heimdal Project Heimdal, Samba Samba.

## How do I fix CVE-2018-16860?

Upgrade to a fixed version.

## Is CVE-2018-16860 being exploited?

There is no known exploitation of CVE-2018-16860 in the wild and no public exploit code.

## Other vulnerabilities in Samba Samba

- [CVE-2022-44640](https://insights.sbomify.com/CVE-2022-44640/): Use after free in n/a (critical 9.8)
- [CVE-2022-42898](https://insights.sbomify.com/CVE-2022-42898/): Integer overflow in n/a (high 8.8)
- [CVE-2022-3116](https://insights.sbomify.com/CVE-2022-3116/): Null dereference in Heimdal Software Kerberos (high 7.5)
- [CVE-2022-45142](https://insights.sbomify.com/CVE-2022-45142/): Security feature bypass in Samba (high 7.5)
- [CVE-2021-44758](https://insights.sbomify.com/CVE-2021-44758/): Null dereference in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-16860 and fix it if it is affected.

What it is: CVE-2018-16860 is a high-severity authentication bypass vulnerability in Samba Samba, published on 31 Jul 2019. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2018-16860 in the wild and no public exploit code.

Affected product: Samba Samba. 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-2018-16860/ (Markdown: https://insights.sbomify.com/CVE-2018-16860/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-16860
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-16860
- OSV: https://osv.dev/vulnerability/CVE-2018-16860

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-16860/
Summaries are generated and may contain mistakes; the official description above is the record.