CVE-2021-40438

criticalknown exploitedpublic exploitcovered by 1 sourcefirst seen 2021-12-01

Actively exploited. CVE-2021-40438 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-12-01) — exploitation has been observed in the wild, and US federal agencies are required to remediate it under BOD 22-01. Treat patching as urgent.

Public exploit code is available. Proof-of-concept or working exploit code for CVE-2021-40438 is indexed in GitHub PoC and Nuclei. Expect opportunistic scanning and exploitation attempts — prioritize remediation.

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.

CSIRTS triage

What: A crafted request can cause mod_proxy to forward requests to an attacker-controlled origin server.
Who is affected: Deployments of Apache HTTP Server version 2.4.48 and earlier.
Urgency: Immediate remediation is necessary due to active exploitation and critical severity.
Action: Upgrade to Apache HTTP Server version 2.4.49 or later.

AI-assisted analysis generated from the source advisory — verify against the original.

⚡ Watch CVE-2021-40438

Get an email if CVE-2021-40438 is added to CISA KEV, gains public exploit code, or a new advisory cites it — max one per day, one-click unsubscribe.

Exploitation outlook

Exploitation confirmedAlready exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 100% of all EPSS-scored CVEs.

Exploit availability

Public exploit or proof-of-concept code for CVE-2021-40438 is indexed in these free datasets. Available exploit code raises real-world risk independent of the CVSS score.

GitHub PoCPublic proof-of-concept repositories on GitHub reference this CVE.look it up ↗
NucleiA nuclei-templates detection/PoC template exists for this CVE.look it up ↗

Advisory coverage (1)

criticalexploitedCVE-2021-40438: Apache HTTP Server-Side Request Forgery (SSRF)cisa-kev · 2021-12-01

External references

NVD record for CVE-2021-40438

CVE.org record

CISA KEV catalog

Embed the live status

— this badge updates automatically when the KEV or exploit status changes. How to embed it →

[![CVE-2021-40438 status](https://www.csirts.com/badge/CVE-2021-40438)](https://www.csirts.com/cve/CVE-2021-40438)