vulntracker.iovulntracker.io
© 2026 vulntracker.io

CVE-2021-44224

Possible NULL dereference or SSRF in forward proxy configurations in Apache HTTP Server 2.4.51 and earlier

HIGH
8.2
CVSS Score
Published: December 20, 2021 at 11:20 AM UTC
Updated: June 17, 2026 at 04:12 AM UTC
11 products affected across 6 vendorsmacOSDebian LinuxFedora

Using Apache HTTP Server by Apache Software Foundation?

Get instant alerts when new vulnerabilities affect Apache HTTP Server - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Start FreeSign In
Severity
HIGH8.2
Exploit prediction
EPSS 82%

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).

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

HTTP Server· Apache
95%
2.4.7 ≤ v < 2.4.522.4.7 ≤ v < Apache HTTP Server 2.4*2.4.7
Affected range stops below 2.4.52, so it looks safe — our inference, not a vendor statement
Affected range stops below Apache HTTP Server 2.4*, so it looks safe — our inference, not a vendor statement
macOS· Apple
95%
v < 10.15.711.0 ≤ v < 11.6.612.0.0 ≤ v < 12.410.15.710.15.7 security_update_2020-00110.15.7 security_update_2021-00110.15.7 security_update_2021-00210.15.7 security_update_2021-00310.15.7 security_update_2021-00410.15.7 security_update_2021-00510.15.7 security_update_2021-00610.15.7 security_update_2021-00710.15.7 security_update_2021-00810.15.7 security_update_2022-00110.15.7 security_update_2022-00210.15.7 security_update_2022-003
Affected range stops below 10.15.7, so it looks safe — our inference, not a vendor statement
Affected range stops below 11.6.6, so it looks safe — our inference, not a vendor statement
Affected range stops below 12.4, so it looks safe — our inference, not a vendor statement
Debian Linux· Debiandrupal
95%
10.011.0
Fedora· Fedora Projectrpm
95%
343536
Communications Element Manager· Oracledrupal
95%
v < 9.0
Affected range stops below 9.0, so it looks safe — our inference, not a vendor statement
Communications Operations Monitor· Oracledrupal
95%
4.04.34.45.0
Communications Session Report Manager· Oracledrupal
95%
v < 9.0
Affected range stops below 9.0, so it looks safe — our inference, not a vendor statement
Communications Session Route Manager· Oracledrupal
95%
v < 9.0
Affected range stops below 9.0, so it looks safe — our inference, not a vendor statement
HTTP Server· Oracle
95%
12.2.1.3.012.2.1.4.0
Instantis Enterprisetrack· Oracle
95%
17.117.217.3

References (19)

x_refsource_MISCVendor Advisory
Source: [email protected]
http://httpd.apache.org/security/vulnerabilities_24.html
Mailing Listx_refsource_FULLDISCThird Party Advisory
Source: [email protected]
http://seclists.org/fulldisclosure/2022/May/33
Mailing Listx_refsource_FULLDISCThird Party Advisory
Source: [email protected]
http://seclists.org/fulldisclosure/2022/May/35
Mailing Listx_refsource_FULLDISCThird Party Advisory
Source: [email protected]
http://seclists.org/fulldisclosure/2022/May/38
Mailing Listx_refsource_MLISTThird Party Advisory
Source: [email protected]
http://www.openwall.com/lists/oss-security/2021/12/20/3
Vendor Advisoryx_refsource_FEDORA
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BFSWOH4X77CV7AH7C4RMHUBDWKQDL4YH/
Vendor Advisoryx_refsource_FEDORA
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RGWILBORT67SHMSLYSQZG2NMXGCMPUZO/
Vendor Advisoryx_refsource_FEDORA
Source: [email protected]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/X73C35MMMZGBVPQQCH7LQZUMYZNQA5FO/

CVSS

8.2HIGH[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-476

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Create accountSign in
Free plan, no card