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Vulnerability details: VCID-db6k-j9mj-e7hy
Vulnerability ID VCID-db6k-j9mj-e7hy
Aliases CVE-2021-33193
Summary A crafted method sent through HTTP/2 will bypass validation and be forwarded by mod_proxy, which can lead to request splitting or cache poisoning. This issue affects Apache HTTP Server 2.4.17 to 2.4.48.
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-476 NULL Pointer Dereference
System Score Found at
cvssv3 7.5 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-33193.json
epss 0.00569 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00569 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00569 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00739 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00739 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00739 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00739 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00739 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00739 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00739 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00739 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00739 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
epss 0.00739 https://api.first.org/data/v1/epss?cve=CVE-2021-33193
cvssv3.1 9.1 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
apache_httpd moderate https://httpd.apache.org/security/json/CVE-2021-33193.json
archlinux High https://security.archlinux.org/AVG-2289
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-33193.json
https://api.first.org/data/v1/epss?cve=CVE-2021-33193
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-33193
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
1966728 https://bugzilla.redhat.com/show_bug.cgi?id=1966728
AVG-2289 https://security.archlinux.org/AVG-2289
CVE-2021-33193 https://httpd.apache.org/security/json/CVE-2021-33193.json
GLSA-202208-20 https://security.gentoo.org/glsa/202208-20
RHSA-2022:1915 https://access.redhat.com/errata/RHSA-2022:1915
RHSA-2022:6753 https://access.redhat.com/errata/RHSA-2022:6753
RHSA-2022:7143 https://access.redhat.com/errata/RHSA-2022:7143
RHSA-2022:7144 https://access.redhat.com/errata/RHSA-2022:7144
USN-5090-1 https://usn.ubuntu.com/5090-1/
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-33193.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.6858
EPSS Score 0.00569
Published At April 21, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-01T12:36:23.122404+00:00 Apache HTTPD Importer Import https://httpd.apache.org/security/json/CVE-2021-33193.json 38.0.0