CVE-2021-33193

moderate-risk
Published 2021-08-16

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.

Do I need to act?

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0.74% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
7
CVSS 7.5/10 High
NETWORK / LOW complexity

Affected Products (7)

Affected Vendors

Debian Apache Oracle Fedoraproject Tenable

References (26)

Patch https://github.com/apache/httpd/commit/ecebcc035ccd8d0e2984fe41420d9e944f456b3c....
Patch https://lists.apache.org/thread.html/re4162adc051c1a0a79e7a24093f3776373e8733aba...
Patch https://lists.apache.org/thread.html/ree7519d71415ecdd170ff1889cab552d71758d2ba2...
Mailing List https://lists.debian.org/debian-lts-announce/2023/03/msg00002.html
Third Party Advisory https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro...
Third Party Advisory https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro...
Exploit https://portswigger.net/research/http2
Third Party Advisory https://security.gentoo.org/glsa/202208-20
Third Party Advisory https://security.netapp.com/advisory/ntap-20210917-0004/
Third Party Advisory https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-a...
Patch https://www.oracle.com/security-alerts/cpuapr2022.html
Patch https://www.oracle.com/security-alerts/cpujan2022.html
Third Party Advisory https://www.tenable.com/security/tns-2021-17
Patch https://github.com/apache/httpd/commit/ecebcc035ccd8d0e2984fe41420d9e944f456b3c....
Patch https://lists.apache.org/thread.html/re4162adc051c1a0a79e7a24093f3776373e8733aba...
Patch https://lists.apache.org/thread.html/ree7519d71415ecdd170ff1889cab552d71758d2ba2...
Mailing List https://lists.debian.org/debian-lts-announce/2023/03/msg00002.html
Third Party Advisory https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro...
Third Party Advisory https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro...
Exploit https://portswigger.net/research/http2
and 6 more references
42
/ 100
moderate-risk
Severity 26/34 · High
Exploitability 2/34 · Minimal
Exposure 14/34 · Moderate