Is CVE-2021-40438 actively exploited?

Yes. CVE-2021-40438 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, which means exploitation in the wild has been confirmed.

Can CVE-2021-40438 be exploited remotely?

The attack vector of CVE-2021-40438 has not been classified yet.

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

CVE-2021-40438 has not received a CVSS score yet.

HOME VULNERABILITIESCVE-2021-40438

HIGHCISA KEVIN THE WILD

CVE-2021-40438

Published: December 1, 2021

EPSS:94.43%probability of exploitation in 30 daysPercentile:100.0th

Official Description

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.

NVD Source

CISA KEV Advisory

Apache HTTP Server-Side Request Forgery (SSRF)

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.

Added to KEV: 2021-12-01Federal patch deadline: 2021-12-15

Required Action (CISA)

Apply updates per vendor instructions.

Risk Analysis

This vulnerability in Apache HTTP Server's mod_proxy module allows an attacker to manipulate request paths, potentially redirecting requests to an arbitrary origin server. Given its high EPSS score and confirmed exploitation, this flaw poses a significant and active risk. The ability for a remote user to choose the origin server can lead to various attacks, including data exfiltration or further compromise.

Active exploitation of this vulnerability has been observed in the wild, indicating a high likelihood of compromise. It is also listed in CISA's KEV catalog, confirming its active exploitation by threat actors. The nature of the flaw suggests it is remotely exploitable.

Recommended Action

Administrators should update their Apache HTTP Server installations to a version beyond 2.4.48 to address this vulnerability. Reviewing mod_proxy configurations for any unusual or overly permissive settings is also recommended.

Generated by the CTIWATCH analysis pipeline from this CVE's metadata (CVSS, EPSS, KEV status, exploit intelligence). Verify against vendor advisories before acting.

Technical Analysis

CVE-2021-40438 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CISA has added CVE-2021-40438 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.