UnratedApache Software Foundation Exploited CISA KEV Updated

Unknown [CVE-2021-40438] mod_proxy SSRF

This security Apache Software Foundation advisory covers CVE-2021-40438 affecting Apache HTTP Server.

CVE-2021-40438 Published Sep 16, 2021Updated by vendor Aug 1, 2026

CVE-2021-40438

Affected products & platforms

Apache Software FoundationHTTP Server

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Summary

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.

CISA Known Exploited Vulnerability

Listed:: Dec 1, 2021 · federal remediation due Dec 15, 2021
Required action:: Apply updates per vendor instructions.
Ransomware use:: Known

KEV is a prioritization signal from CISA — remediation detail still comes from the vendor advisory.

Affected versions

Apache HTTP Server Apache HTTP Server 2.4 through 2.4.48

Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source

Fixed versions

No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.

Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source

Mitigation

The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.

Official advisory · medium-confidence parse· fetched 2 hours ago·verify at source

Sources

Official and corroborating records used to build this advisory.

Official vendor advisoryofficial
Official advisory page fetched and parsed for the summary, affected/fixed versions and remediation guidance it provides.
Apache Software Foundation
CVE.org CNA recordCVE.org
Independent CNA record used for near-real-time discovery and missed-CVE reconciliation. Discovered from the machine-readable feed https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/delta.json; this link opens the CVE.org record for CVE-2021-40438 instead of the raw feed document.
CVE Program

Cross-references

Validate CVE metadata against the authoritative registries.

CVE-2021-40438NVD CVE.org MITRE

Official resources

Apache HTTP Server 2.4 vulnerabilities (official fixed-in table)
Official documentation
Official upgrade documentation for Apache HTTP Server 2.4 vulnerabilities (official fixed-in table).
ASF Security — reporting & CVE process
Official documentation
The Apache Software Foundation's official security page: how ASF CVEs are published and where each project's advisories live.
Apache project downloads (fixed releases)
Official documentation
Official ASF download tree — fetch the fixed release named in this advisory from the project's directory.

Discussion(0)

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