CVE-2021-44224
Possible NULL dereference or SSRF in forward proxy configurations in Apache HTTP Server 2.4.51 and earlier
02 Description
Possible NULL dereference or SSRF in forward proxy configurations in Apache HTTP Server 2.4.51 and earlier
03 Exploitation and scoring
- Exploitation
- Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
- SSVC decision
- Not assessed by CISA
- EPSS probability
- 82.29% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 99.6% of scored records. A rank, not a probability.
- NVD base score
- 8.2 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
- NVD analysis status
- Modified. NVD last modified this record on 2026-06-17.
- Red Hat severity
- Moderate. Red Hat's rating for its own products, not a CVSS rating.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2021-12-20 11:20Z4 YR AGO
- Last updated
- 2024-08-04 04:17Z2 YR AGO
- Reserved
- 2021-11-25
- Assigning CNA
- apache
- Record state
- PUBLISHED
- Severity
- Not rated by the issuing CNA
- CNA CVSS vector
- Not published by the issuing CNA
- Weaknesses
- Data version
- 5.1
- Document digest
- e431bff77ea8d0d9eb68a36b385f850315f99674bb756e0cf28db8ff377e7cfe
05 Affected products
06 References
- httpd.apache.orghttp://httpd.apache.org/security/vulnerabilities_24.html
- www.openwall.com[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 earlierhttp://www.openwall.com/lists/oss-security/2021/12/20/3
- lists.fedoraproject.orgFEDORA-2021-29a536c2aehttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BFSWOH4X77CV7AH7C4RMHUBDWKQDL4YH/
- www.debian.orgDSA-5035https://www.debian.org/security/2022/dsa-5035
- www.oracle.comhttps://www.oracle.com/security-alerts/cpujan2022.html
- security.netapp.comhttps://security.netapp.com/advisory/ntap-20211224-0001/
- www.tenable.comhttps://www.tenable.com/security/tns-2022-01
- www.tenable.comhttps://www.tenable.com/security/tns-2022-03
- lists.fedoraproject.orgFEDORA-2022-b4103753e9https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RGWILBORT67SHMSLYSQZG2NMXGCMPUZO/
- lists.fedoraproject.orgFEDORA-2022-21264ec6dbhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z7H26WJ6TPKNWV3QKY4BHKUKQVUTZJTD/
- lists.fedoraproject.orgFEDORA-2022-78e3211c55https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/X73C35MMMZGBVPQQCH7LQZUMYZNQA5FO/
- www.oracle.comhttps://www.oracle.com/security-alerts/cpuapr2022.html
- support.apple.comhttps://support.apple.com/kb/HT213257
- support.apple.comhttps://support.apple.com/kb/HT213256
- support.apple.comhttps://support.apple.com/kb/HT213255
- seclists.org20220516 APPLE-SA-2022-05-16-4 Security Update 2022-004 Catalinahttp://seclists.org/fulldisclosure/2022/May/33
- seclists.org20220516 APPLE-SA-2022-05-16-3 macOS Big Sur 11.6.6http://seclists.org/fulldisclosure/2022/May/35
- seclists.org20220516 APPLE-SA-2022-05-16-2 macOS Monterey 12.4http://seclists.org/fulldisclosure/2022/May/38
- security.gentoo.orgGLSA-202208-20https://security.gentoo.org/glsa/202208-20
07 Fixed in
AlmaLinux 8
- httpd Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- httpd-devel Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- httpd-filesystem Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- httpd-manual Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- httpd-tools Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- mod_http2 Fixed in 1.15.7-5.module_el8.6.0+2872+fe0ff7aa
- mod_ldap Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- mod_md Fixed in 1:2.0.8-8.module_el8.6.0+2872+fe0ff7aa
- mod_proxy_html Fixed
A version is affected if any line below covers it.
- Affected before 1:2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 1:2.4.37-47.module_el8.6.0+2935+fb177b09.2
- mod_session Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- mod_ssl Fixed
A version is affected if any line below covers it.
- Affected before 1:2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 1:2.4.37-47.module_el8.6.0+2935+fb177b09.2
Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
CloudLinux 8
- httpd Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- httpd-devel Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- httpd-filesystem Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- httpd-manual Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- httpd-tools Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- mod_http2 Fixed in 1.15.7-5.module_el8.6.0+2872+fe0ff7aa
- mod_ldap Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- mod_md Fixed in 1:2.0.8-8.module_el8.6.0+2872+fe0ff7aa
- mod_proxy_html Fixed
A version is affected if any line below covers it.
- Affected before 1:2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 1:2.4.37-47.module_el8.6.0+2935+fb177b09.2
- mod_session Fixed
A version is affected if any line below covers it.
- Affected before 2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 2.4.37-47.module_el8.6.0+2935+fb177b09.2
- mod_ssl Fixed
A version is affected if any line below covers it.
- Affected before 1:2.4.37-47.module_el8.6.0+2872+fe0ff7aa.1.alma
- Affected before 1:2.4.37-47.module_el8.6.0+2935+fb177b09.2
Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.
Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.
Debian 12
- apache2 Fixed in 2.4.52-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- apache2 Fixed in 2.4.52-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- apache2 Fixed in 2.4.52-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 18.04 LTS
- apache2 Fixed in 2.4.29-1ubuntu4.21
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 20.04 LTS
- apache2 Fixed in 2.4.41-4ubuntu3.9
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 22.04 LTS
- apache2 Fixed in 2.4.52-1ubuntu1
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 14.04 LTS
- apache2 Fixed in 2.4.7-1ubuntu4.22+esm3Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu Pro 16.04 LTS
- apache2 Fixed in 2.4.18-2ubuntu3.17+esm4Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.