# CVE-2021-44224: Possible NULL dereference or SSRF in forward proxy configurations in Apache HTTP Server 2.4.51 and earlier


- **Severity:** High 8.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 20 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** ALPINE-CVE-2021-44224, AZL-7043, BIT-apache-2021-44224, CLEANSTART-2026-GK10724, DEBIAN-CVE-2021-44224, GHSA-92ww-hwmg-qq7p, UBUNTU-CVE-2021-44224

## What is CVE-2021-44224?

CVE-2021-44224 is a high-severity vulnerability in Apache Http Server, published on 20 Dec 2021. 

### Official description

A crafted URI sent to httpd configured as a forward proxy (ProxyRequests on) can cause a crash (NULL pointer dereference) or, for configurations mixing forward and reverse proxy declarations, can allow for requests to be directed to a declared Unix Domain Socket endpoint (Server Side Request Forgery). This issue affects Apache HTTP Server 2.4.7 up to 2.4.51 (included).

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-44224?

1 open source package ship an affected version, including apache. It affects 12 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `apache` | Bitnami | From 2.4.7 | 2.4.52 |

Products: Apache Http Server, Apple Mac Os X, Apple Macos, Debian Debian Linux, Fedoraproject Fedora, Oracle Communications Element Manager, Oracle Communications Operations Monitor, Oracle Communications Session Report Manager, Oracle Communications Session Route Manager, Oracle Http Server, Oracle Instantis Enterprisetrack, Tenable Tenable.sc.

## How do I fix CVE-2021-44224?

Upgrade apache to 2.4.52 or later.

## Is CVE-2021-44224 being exploited?

There is no known exploitation of CVE-2021-44224 in the wild and no public exploit code.

## 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-2021-44224 and fix it if it is affected.

What it is: CVE-2021-44224 is a high-severity vulnerability in Apache Http Server, published on 20 Dec 2021. 
Exploitation: There is no known exploitation of CVE-2021-44224 in the wild and no public exploit code.

Affected packages and fixed versions:
- apache (Bitnami): affected from 2.4.7; fixed in 2.4.52

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-2021-44224/ (Markdown: https://insights.sbomify.com/CVE-2021-44224/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-44224
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-44224
- OSV: https://osv.dev/vulnerability/CVE-2021-44224

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-44224/
Summaries are generated and may contain mistakes; the official description above is the record.