CVE-2021-44224

Name: CVE-2021-44224
Creator: NVD / NIST
Published: 2021-12-20T12:15:07.393+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.2/10EPSS 82.30%

Last modified Jun 17, 2026

CVE-2021-44224 is a high-severity vulnerability rated 8.2/10 on the CVSS scale. 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).. EPSS estimates a 82.30% chance of exploitation in the next 30 days.

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).

Metrics

CVSS 3.1

8.2/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

EPSS Probability

82.30%

99.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Apache	Http Server	>= 2.4.7, < 2.4.52
Fedoraproject	Fedora	34
Fedoraproject	Fedora	35
Fedoraproject	Fedora	36
Debian	Debian Linux	10.0
Debian	Debian Linux	11.0
Tenable	Tenable.Sc	>= 5.14.0, < 5.20.0
Tenable	Tenable.Sc	>= 5.16.0, < 202201.1
Oracle	Communications Element Manager	< 9.0
Oracle	Communications Operations Monitor	4.0
Oracle	Communications Operations Monitor	4.3
Oracle	Communications Operations Monitor	4.4
Oracle	Communications Operations Monitor	5.0
Oracle	Communications Session Report Manager	< 9.0
Oracle	Communications Session Route Manager	< 9.0
Oracle	Http Server	All versions
Oracle	Http Server	12.2.1.3.0
Oracle	Http Server	12.2.1.4.0
Oracle	Instantis Enterprisetrack	17.1
Oracle	Instantis Enterprisetrack	17.2
Oracle	Instantis Enterprisetrack	17.3
Apple	Mac Os X	10.15.7
Apple	Macos	< 10.15.7
Apple	Macos	>= 11.0, < 11.6.6
Apple	Macos	>= 12.0.0, < 12.4

References

http://httpd.apache.org/security/vulnerabilities_24.htmlVendor Advisory
http://seclists.org/fulldisclosure/2022/May/33Mailing List, Third Party Advisory
http://seclists.org/fulldisclosure/2022/May/35Mailing List, Third Party Advisory
http://seclists.org/fulldisclosure/2022/May/38Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/12/20/3Mailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BFSWOH4X77CV7AH7C4RMHUBDWKQDL4YH/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RGWILBORT67SHMSLYSQZG2NMXGCMPUZO/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/X73C35MMMZGBVPQQCH7LQZUMYZNQA5FO/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7H26WJ6TPKNWV3QKY4BHKUKQVUTZJTD/
https://security.gentoo.org/glsa/202208-20Third Party Advisory
https://security.netapp.com/advisory/ntap-20211224-0001/Third Party Advisory
https://support.apple.com/kb/HT213255Third Party Advisory
https://support.apple.com/kb/HT213256Third Party Advisory
https://support.apple.com/kb/HT213257Third Party Advisory
https://www.debian.org/security/2022/dsa-5035Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
https://www.tenable.com/security/tns-2022-01Third Party Advisory
https://www.tenable.com/security/tns-2022-03Third Party Advisory
http://httpd.apache.org/security/vulnerabilities_24.htmlVendor Advisory
http://seclists.org/fulldisclosure/2022/May/33Mailing List, Third Party Advisory
http://seclists.org/fulldisclosure/2022/May/35Mailing List, Third Party Advisory
http://seclists.org/fulldisclosure/2022/May/38Mailing List, Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/12/20/3Mailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BFSWOH4X77CV7AH7C4RMHUBDWKQDL4YH/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RGWILBORT67SHMSLYSQZG2NMXGCMPUZO/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/X73C35MMMZGBVPQQCH7LQZUMYZNQA5FO/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7H26WJ6TPKNWV3QKY4BHKUKQVUTZJTD/
https://security.gentoo.org/glsa/202208-20Third Party Advisory
https://security.netapp.com/advisory/ntap-20211224-0001/Third Party Advisory
https://support.apple.com/kb/HT213255Third Party Advisory
https://support.apple.com/kb/HT213256Third Party Advisory
https://support.apple.com/kb/HT213257Third Party Advisory
https://www.debian.org/security/2022/dsa-5035Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
https://www.tenable.com/security/tns-2022-01Third Party Advisory
https://www.tenable.com/security/tns-2022-03Third Party Advisory

Timeline

Published: Dec 20, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-44224?

How severe is CVE-2021-44224?

CVE-2021-44224 has a CVSS score of 8.2/10 (HIGH severity). The EPSS model estimates a 82.30% probability of exploitation in the next 30 days.

How do I fix CVE-2021-44224?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-44224?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST