# CVE-2018-16845: Denial of service in nginx

> Attackers can cause worker crashes, infinite loops, or memory disclosure via crafted MP4 files in nginx when the optional MP4 module is enabled.

- **Severity:** High 8.2 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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:** 7 Nov 2018
- **Updated:** 5 Aug 2024
- **Also known as:** ALPINE-CVE-2018-16845, CLEANSTART-2026-DQ45317, DEBIAN-CVE-2018-16845, DLA-1572-1, GHSA-vq5f-vpgw-9vcp, RHSA-2018:3652, UBUNTU-CVE-2018-16845

## What is CVE-2018-16845?

CVE-2018-16845 is a high-severity denial of service vulnerability in Apple Xcode, published on 7 Nov 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

nginx before versions 1.15.6, 1.14.1 has a vulnerability in the ngx_http_mp4_module, which might allow an attacker to cause infinite loop in a worker process, cause a worker process crash, or might result in worker process memory disclosure by using a specially crafted mp4 file. The issue only affects nginx if it is built with the ngx_http_mp4_module (the module is not built by default) and the .mp4. directive is used in the configuration file. Further, the attack is only possible if an attacker is able to trigger processing of a specially crafted mp4 file with the ngx_http_mp4_module.

Weakness: CWE-835 (Loop with Unreachable Exit Condition), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2018-16845?

It affects 5 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `rh-nginx18-nginx` | Red Hat:rhel_software_collections:3::el6 | All versions | 1:1.8.1-1.el6.1 |
| `rh-nginx18-nginx-debuginfo` | Red Hat:rhel_software_collections:3::el6 | All versions | 1:1.8.1-1.el6.1 |
| `rh-nginx18-nginx` | Red Hat:rhel_software_collections:3::el7 | All versions | 1:1.8.1-1.el7.1 |
| `rh-nginx18-nginx-debuginfo` | Red Hat:rhel_software_collections:3::el7 | All versions | 1:1.8.1-1.el7.1 |

Products: Apple Xcode, Canonical Ubuntu Linux, Debian Debian Linux, F5 Nginx, Opensuse Leap.

## How do I fix CVE-2018-16845?

Upgrade to a fixed version.

## Is CVE-2018-16845 being exploited?

There is no known exploitation of CVE-2018-16845 in the wild and no public exploit code.

## Other vulnerabilities in Apple Xcode

- [CVE-2025-48384](https://insights.sbomify.com/CVE-2025-48384/): Git Link Following (high 8.1, exploited in the wild)
- [CVE-2014-9390](https://insights.sbomify.com/CVE-2014-9390/): JGit Improper Input Validation vulnerability (critical 9.8)
- [CVE-2019-14379](https://insights.sbomify.com/CVE-2019-14379/): Deserialization of untrusted data in FasterXML jackson-databind (critical 9.8)
- [CVE-2018-4164](https://insights.sbomify.com/CVE-2018-4164/): An issue was discovered in certain Apple products. (critical 9.8)
- [CVE-2016-0746](https://insights.sbomify.com/CVE-2016-0746/): Use after free in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-16845 and fix it if it is affected.

What it is: CVE-2018-16845 is a high-severity denial of service vulnerability in Apple Xcode, published on 7 Nov 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-2018-16845 in the wild and no public exploit code.

Affected product: Apple Xcode. 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-2018-16845/ (Markdown: https://insights.sbomify.com/CVE-2018-16845/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-16845
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-16845
- OSV: https://osv.dev/vulnerability/CVE-2018-16845

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-16845/
Summaries are generated and may contain mistakes; the official description above is the record.