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CVE-2021-33193

Request splitting via HTTP/2 method injection and mod_proxy

Published: Aug 16, 2021Updated: May 1, 2025 Sources: CVE List NVD BDUNVD-CWE-Other
7.5HIGH
NVD MITRE
EPSS Score
46.2%
Top 1.3%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
Nuclei · OpenVAS

Description

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:HIntegrity
High
A:NAvailability
None
Open in CVSS calculator →

Weaknesses

NVD-CWE-Other

Affected Products

ООО «РусБИТех-Астра»
commercial·RUaka rusbitech-astra
Astra Linux Special EditionOn-premOS
Operating Systems / linux-distro
Astra Linux Common EditionOn-premOS
Operating Systems / linux-distro
Astra Linux Special Edition для «Эльбрус»On-premOS
Operating Systems / linux-distro
oracle
commercial·USaka oracle corp.
secure backupOn-prem
Databases
zfs storage appliance kitOn-premDatabase
Databases / data-warehouse-analytics
АО «НТЦ ИТ РОСА»
commercial·RU
ROSA VirtualizationOn-prem
Operating Systems / linux-distro
ROSA Virtualization 3.0On-prem
Operating Systems / linux-distro
debian
oss-project·GBaka debian gnu/linux
debian linuxOn-premOS
Operating Systems / linux-distro
apache
oss-project·USaka apache httpd, apache http server
http serverOn-premWeb App
Networking Infrastructure / load-balancer-proxy
fedoraproject
oss-project·USaka fedora project
fedoraOn-premOS
Operating Systems / linux-distro
and 7 more affected products View all →

Exploitability

Official Patch Available
Is your org exposed to CVE-2021-33193?We'll check your whole external perimeter for exposure — free. Check my exposure

References

https://github.com/apache/httpd/commit/ecebcc035ccd8d0e2984fe41420d9e944f456b3c.patch
github.com
https://lists.apache.org/thread.html/re4162adc051c1a0a79e7a24093f3776373e8733abaff57253fef341d%40%3Ccvs.httpd.apache.org%3E
lists.apache.org
https://lists.apache.org/thread.html/ree7519d71415ecdd170ff1889cab552d71758d2ba2904a17ded21a70%40%3Ccvs.httpd.apache.org%3E
lists.apache.org
and 32 more references View all →

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