# CVE-2018-8011: mod_md, DoS via Coredumps on specially crafted requests

> Attackers can cause a denial of service by sending crafted HTTP requests that trigger a null pointer dereference in the mod_md module.

- **Severity:** High 7.5 (`CVSS:3.0/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:** 18 Jul 2018
- **Updated:** 16 Sep 2024
- **Also known as:** ALPINE-CVE-2018-8011, CLEANSTART-2026-GS47054, DEBIAN-CVE-2018-8011

## What is CVE-2018-8011?

CVE-2018-8011 is a high-severity vulnerability in Apache Http Server, published on 18 Jul 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

By specially crafting HTTP requests, the mod_md challenge handler would dereference a NULL pointer and cause the child process to segfault. This could be used to DoS the server. Fixed in Apache HTTP Server 2.4.34 (Affected 2.4.33).

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2018-8011?

It affects 2 products.


Products: Apache Http Server, Netapp Cloud Backup.

## How do I fix CVE-2018-8011?

Upgrade to a fixed version.

## Is CVE-2018-8011 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2018-8011 exists.

Public exploit code:

- Apache HTTP Server - NULL Pointer Dereference (nuclei)

## Other vulnerabilities in Apache Http Server

- [CVE-2021-42013](https://insights.sbomify.com/CVE-2021-42013/): Apache HTTP Server Path Traversal (critical 9.8, exploited in the wild)
- [CVE-2024-38475](https://insights.sbomify.com/CVE-2024-38475/): Apache HTTP Server Improper Escaping of Output (critical 9.1, exploited in the wild)
- [CVE-2021-40438](https://insights.sbomify.com/CVE-2021-40438/): Apache HTTP Server-Side Request Forgery (SSRF) (critical 9.0, exploited in the wild)
- [CVE-2019-0211](https://insights.sbomify.com/CVE-2019-0211/): Apache HTTP Server Privilege Escalation (high 7.8, exploited in the wild)
- [CVE-2021-41773](https://insights.sbomify.com/CVE-2021-41773/): Apache HTTP Server Path Traversal (high 7.5, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-8011 and fix it if it is affected.

What it is: CVE-2018-8011 is a high-severity vulnerability in Apache Http Server, published on 18 Jul 2018. 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-2018-8011 exists.

Affected product: Apache Http Server. 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-2018-8011/ (Markdown: https://insights.sbomify.com/CVE-2018-8011/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-8011
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-8011
- OSV: https://osv.dev/vulnerability/CVE-2018-8011

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-8011/
Summaries are generated and may contain mistakes; the official description above is the record.