high
8.2
CWE
476 918 119
Advisory Published
CVE Published
Updated

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

First published: Mon Dec 20 2021(Updated: )

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).

Credit: CVE-2021-44224 CVE-2021-44790 CVE-2022-22719 CVE-2022-22720 CVE-2022-22721 Lockheed Martin Red Team an anonymous researcher Jeremy Brown Trend Micro Zero Day InitiativeMichael DePlante @izobashi Trend Micro Zero Day InitiativeQi Sun Trend MicroYe Zhang @co0py_Cat Baidu SecurityRobert Ai Trend MicroArsenii Kostromin (0x3c3e) Yonghwi Jin @jinmo123 TheoriLinus Henze Pinauten GmbHLiu Long Ant Security LightJack Dates RET2 Systems IncAntonio Zekic @antoniozekic Jeonghoon Shin Theori working with Trend Micro Zero Day InitiativePeter Nguyễn Vũ Hoàng @peternguyen14 STAR LabsNed Williamson Google Project Zero @gorelics BreakPoint BreakPointRon Masas BreakPointWojciech Reguła @_r3ggi SecuRingArsenii Kostromin (0x3c3e) MicrosoftJonathan Bar Or MicrosoftZhipeng Huo @R3dF09 Tencent Security Xuanwu LabYuebin Sun @yuebinsun2020 Tencent Security Xuanwu LabMax Shavrick @_mxms the Google Security TeamZubair Ashraf CrowdstrikeCVE-2022-0778 CVE-2022-23308 Mickey Jin @patch1t @gorelics Peter Nguyễn Vũ Hoàng STAR LabsFelix Poulin-Belanger Antonio Cheong Yu Xuan YCISCQCVE-2021-4136 CVE-2021-4166 CVE-2021-4173 CVE-2021-4187 CVE-2021-4192 CVE-2021-4193 CVE-2021-46059 CVE-2022-0128 Heige KnownSec 404 TeamBo Qu Palo Alto NetworksScarlet Raine Wang Yu CyberservalCVE-2022-0530 Tavis Ormandy CVE-2021-45444 ABC Research s.r.o Jon Thompson EvolveIA) actae0n Blacksun Hackers Club working with Trend Micro Zero Day InitiativeAndrew Williams GoogleAvi Drissman Googlechenyuwang @mzzzz__ Tencent Security Xuanwu LabJordy Zomer @pwningsystems Paul Walker BuryNathaniel Ekoniak Ennate TechnologiesGergely Kalman @gergely_kalman Mandiant MandiantJoshua Mason MandiantRon Waisberg SecuRingan anonymous researcher SecuRing Perception PointRon Hass @ronhass7 Perception Pointryuzaki Chijin Zhou ShuiMuYuLin LtdTsinghua wingtecher lab Jeonghoon Shin TheoriSorryMybad @S0rryMybad Kunlun LabDongzhuo Zhao ADLab of Venustech security@apache.org

Affected SoftwareAffected VersionHow to fix
redhat/jbcs-httpd24-httpd<0:2.4.51-28.el8
0:2.4.51-28.el8
redhat/jbcs-httpd24-httpd<0:2.4.51-28.el7
0:2.4.51-28.el7
redhat/httpd24-httpd<0:2.4.34-23.el7.5
0:2.4.34-23.el7.5
debian/apache2
2.4.38-3+deb10u8
2.4.38-3+deb10u10
2.4.56-1~deb11u2
2.4.56-1~deb11u1
2.4.57-2
2.4.57-3
2.4.58-1
redhat/httpd<2.4.52
2.4.52
Apple macOS Monterey<12.4
12.4
Apple macOS<11.6.6
11.6.6
macOS Catalina
Apache Http Server>=2.4.7<2.4.52
Fedora=34
Fedora=35
Fedora=36
Debian=10.0
Debian=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
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 iOS and macOS=10.15.7
Apple iOS and macOS=10.15.7-security_update_2020-001
Apple iOS and macOS=10.15.7-security_update_2021-001
Apple iOS and macOS=10.15.7-security_update_2021-002
Apple iOS and macOS=10.15.7-security_update_2021-003
Apple iOS and macOS=10.15.7-security_update_2021-004
Apple iOS and macOS=10.15.7-security_update_2021-005
Apple iOS and macOS=10.15.7-security_update_2021-006
Apple iOS and macOS=10.15.7-security_update_2021-007
Apple iOS and macOS=10.15.7-security_update_2021-008
Apple iOS and macOS=10.15.7-security_update_2022-001
Apple iOS and macOS=10.15.7-security_update_2022-002
Apple iOS and macOS=10.15.7-security_update_2022-003
Apple iOS and macOS<10.15.7
Apple iOS and macOS>=11.0<11.6.6
Apple iOS and macOS>=12.0.0<12.4

Remedy

https://www.oracle.com/security-alerts/cpuapr2022.html

Remedy

https://www.oracle.com/security-alerts/cpujan2022.html

Remedy

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Never miss a vulnerability like this again

Sign up to SecAlerts for real-time vulnerability data matched to your software, aggregated from hundreds of sources.

Read MoreStart Free Trial

Reference Links

Parent vulnerabilities

(Appears in the following advisories)

Peer vulnerabilities

(Found alongside the following vulnerabilities)

Frequently Asked Questions

  • What is CVE-2021-44224?

    CVE-2021-44224 is a vulnerability in the Apache HTTP server that allows for a null pointer dereference and server-side request forgery (SSRF) when the mod_proxy module is configured as a forward proxy.

  • How does CVE-2021-44224 impact the Apache HTTP server?

    CVE-2021-44224 can cause a crash or allow for SSRF attacks if a crafted packet is sent to the forward proxy on the adjacent network.

  • What is the severity of CVE-2021-44224?

    CVE-2021-44224 has a severity value of 7, indicating a high severity.

  • How can I fix CVE-2021-44224?

    To fix CVE-2021-44224, update Apache HTTP server to version 2.4.53 or later.

  • Are there any references for CVE-2021-44224?

    Yes, you can find references for CVE-2021-44224 at the following links: [Link 1](https://support.apple.com/en-us/HT213257), [Link 2](https://support.apple.com/en-us/HT213255), [Link 3](https://support.apple.com/en-us/HT213256).

Company

Resources

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2025 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203