CVE-2021-33193
Request splitting via HTTP/2 method injection and mod_proxy
7.5
HIGH
CVSS 3.1
EPSS 0.61%
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.
How to fix CVE-2021-33193
To remediate CVE-2021-33193, upgrade the affected package to a fixed version below.
- Alpine/apache2—upgrade to 2.4.49-r0 or later
- —upgrade to 2.4.49 or later
- —upgrade to 2.4.48-3.1+deb11u1 or later
Is CVE-2021-33193 being exploited?
Low — EPSS is 0.6%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0, < 2.4.49-r0
- >= 2.4.17, < 2.4.49
- from 0, < 2.4.48-3.1+deb11u1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
References (16)
- ADVISORYsecurity.alpinelinux.org/vuln/CVE-2021-33193
- ADVISORYsecurity-tracker.debian.org/tracker/CVE-2021-33193
- WEBgithub.com/apache/httpd/commit/ecebcc035ccd8d0e2984fe41420d9e944f456b3c.patch
- WEBlists.apache.org/thread.html/re4162adc051c1a0a79e7a24093f3776373e8733abaff57253fef341d%40%3Ccvs.httpd.apache.org%3E