SARA / Free Tools / CVE / CVE-2021-40438

CVE-2021-40438 — A crafted request uri-path can cause mod_proxy to forward the request to an orig

A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user. This issue affects Apache HTTP Server 2.4.48 and earlier.

CVSS
9.0 CRITICAL
EPSS
100.00% (top 0.00%)
CWE
—
Published
2021-09-16T15:15:07.633
Last modified
2026-08-06T05:16:35.670
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
CISA KEV — Actively Exploited
Added to KEV
2021-12-01
BOD 22-01 due
—
Ransomware use
Known
View KEV detail
CVE-2021-40438 on CISA KEV →

01What is this vulnerability?

A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user. This issue affects Apache HTTP Server 2.4.48 and earlier.

02Affected products

No structured affected-product list available — see references below for vendor advisories.

03Active exploitation status

Yes — actively exploited. Added to the CISA KEV catalog on 2021-12-01. Ransomware use: Known.

04Recommended remediation

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection in your stack of choice:

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07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

09References

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