CVE-2021-33193
CVSS v3
7.5
HIGH
EPSS Score
46.2 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
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.
Technical details
- Published
- 2021-08-16
Frequently asked questions
What is CVE-2021-33193?
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.
Is CVE-2021-33193 actively exploited?
Active exploitation of CVE-2021-33193 has not been confirmed. Its EPSS score was 46.2% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2021-33193?
CVE-2021-33193 has a CVSS v3 base score of 7.5 (HIGH severity).
Is CVE-2021-33193 affecting your environment?
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