---
title: "CVE-2021-44224: Possible NULL dereference or SSRF… | CubePath"
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…"
language: en
source: https://cubepath.com/security/cve/CVE-2021-44224
---

# CVE-2021-44224: Possible NULL dereference or SSRF… | CubePath

## 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).

Official description from the CVE record, published by apache. Copyright © 1999-2026 The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-44224)

## Key data

### EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.

Score

0.82295 (82.3% probability)

Percentile

99.7%

Scores of

Nov 10, 2026

Model

v2026.06.15

### Weakness (CWE)

CWE catalog version 5.0.

CWE names: Copyright © 2006-2026, The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CWE license.

- [CWE-476](https://cwe.mitre.org/data/definitions/476.html) NULL Pointer Dereference

## Affected products

Products listed in the CVE record, as the CNA published them.

- Apache HTTP Server

  - affected: 2.4.7 up to before Apache HTTP Server 2.4\*

## References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

- [httpd.apache.org/security/vulnerabilities\_24.html](http://httpd.apache.org/security/vulnerabilities%5F24.html)
- [\[oss-security\] 20211220 CVE-2021-44224: Apache HTTP Server: Possible NULL dereference or SSRF in forward proxy configurations in Apache HTTP Server 2.4.51 and earlier](http://www.openwall.com/lists/oss-security/2021/12/20/3)  (openwall.com) mailing-list
- [FEDORA-2021-29a536c2ae](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BFSWOH4X77CV7AH7C4RMHUBDWKQDL4YH/)  (lists.fedoraproject.org) vendor-advisory
- [DSA-5035](https://www.debian.org/security/2022/dsa-5035)  (debian.org) vendor-advisory
- [oracle.com/security-alerts/cpujan2022.html](https://www.oracle.com/security-alerts/cpujan2022.html)
- [security.netapp.com/advisory/ntap-20211224-0001](https://security.netapp.com/advisory/ntap-20211224-0001/)
- [tenable.com/security/tns-2022-01](https://www.tenable.com/security/tns-2022-01)
- [tenable.com/security/tns-2022-03](https://www.tenable.com/security/tns-2022-03)
- [FEDORA-2022-b4103753e9](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RGWILBORT67SHMSLYSQZG2NMXGCMPUZO/)  (lists.fedoraproject.org) vendor-advisory
- [FEDORA-2022-21264ec6db](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7H26WJ6TPKNWV3QKY4BHKUKQVUTZJTD/)  (lists.fedoraproject.org) vendor-advisory
- [FEDORA-2022-78e3211c55](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/X73C35MMMZGBVPQQCH7LQZUMYZNQA5FO/)  (lists.fedoraproject.org) vendor-advisory
- [oracle.com/security-alerts/cpuapr2022.html](https://www.oracle.com/security-alerts/cpuapr2022.html)
- [support.apple.com/kb/HT213257](https://support.apple.com/kb/HT213257)
- [support.apple.com/kb/HT213256](https://support.apple.com/kb/HT213256)
- [support.apple.com/kb/HT213255](https://support.apple.com/kb/HT213255)
- [20220516 APPLE-SA-2022-05-16-4 Security Update 2022-004 Catalina](http://seclists.org/fulldisclosure/2022/May/33)  (seclists.org) mailing-list
- [20220516 APPLE-SA-2022-05-16-3 macOS Big Sur 11.6.6](http://seclists.org/fulldisclosure/2022/May/35)  (seclists.org) mailing-list
- [20220516 APPLE-SA-2022-05-16-2 macOS Monterey 12.4](http://seclists.org/fulldisclosure/2022/May/38)  (seclists.org) mailing-list
- [GLSA-202208-20](https://security.gentoo.org/glsa/202208-20)  (security.gentoo.org) vendor-advisory

## Timeline

1. ID reserved Nov 25, 2021
2. Record published Dec 20, 2021
3. Record last updated Aug 4, 2024

## Look up another CVE

## About CubePath

CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection.

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Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 20:05 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)