CVE-2021-33193 - CVE House
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Status published High CVE-2021-33193

Request splitting via HTTP/2 method injection and mod_proxy

Vulnerability 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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

The following person or organization is credited with identifying this vulnerability, as recorded in the NVD database:

  • Reported by James Kettle of PortSwigger

References

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Affected Vendor

Apache Software Foundation

View all reports →

Affected Software

Apache HTTP Server
Vulnerable Versions:
Apache HTTP Server 2.4 2.4.17 to 2.4.48

Timeline

Official Publish: August 16th, 2021
Last Modified: August 3rd, 2024
Added to House: July 21st, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Weaknesses (CWE)

No CWE data available

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.