What is the CVSS score of CVE-2021-40438?

CVE-2021-40438 has a CVSS 3.1 base score of 9.0 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H. EPSS exploitation probability: 100.0%.

Is there a public PoC exploit available for CVE-2021-40438?

Yes, a public proof-of-concept exploit is available for CVE-2021-40438. Prioritise patching immediately. EPSS: 100.0%.

Is there a patch available for CVE-2021-40438?

Yes, a patch is available for CVE-2021-40438. Update the affected software to the latest version immediately.

Rocky Linux CVE-2021-40438

CRITICAL

Server-Side Request Forgery (SSRF) (CWE-918)

2021-09-16 security@apache.org

9.0

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.0 CRITICAL

AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Added to CISA KEV

Jul 14, 2026 - 04:22 CISA

CVE Published

Sep 16, 2021 - 15:15 nvd

CRITICAL 9.0

DescriptionNVD

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.

AnalysisAI

A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user.4.48 and earlier. Rated critical severity (CVSS 9.0), this vulnerability is remotely exploitable, no authentication required. This Server-Side Request Forgery (SSRF) vulnerability could allow attackers to make the server perform requests to unintended internal or external resources.

Technical ContextAI

This vulnerability is classified as Server-Side Request Forgery (SSRF) (CWE-918), which allows attackers to make the server perform requests to unintended internal or external resources. A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user.4.48 and earlier. Affected products include: Resf Rocky Linux, Redhat Enterprise Linux, Redhat Enterprise Linux Eus, Redhat Enterprise Linux For Arm 64, Redhat Enterprise Linux For Arm 64 Eus.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Validate and allowlist destination URLs, block requests to internal networks, use network segmentation.