canonical ubuntu-linux CVE-2021-40438 vulnerability in Canonical and Other Products
Published on September 16, 2021

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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.

Vendor Advisory NVD

Known Exploited Vulnerability

This Apache HTTP Server-Side Request Forgery (SSRF) vulnerability is part of CISA's list of Known Exploited Vulnerabilities. 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.

The following remediation steps are recommended / required by December 15, 2021: Apply updates per vendor instructions.

Vulnerability Analysis

CVE-2021-40438 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. It has an exploitability score of 2.2 out of four. The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.

What is a XSPA Vulnerability?

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.

CVE-2021-40438 has been classified to as a XSPA vulnerability or weakness.


Products Associated with CVE-2021-40438

You can be notified by stack.watch whenever vulnerabilities like CVE-2021-40438 are published in these products:

Canonical Ubuntu Linux
 
Apache HTTP Server
 
Fedora Project Fedora
 
Debian Linux
 
NetApp Clustered Data Ontap
 
NetApp Storagegrid
 
F5 Networks F5os
 
NetApp Cloud Backup
 
Oracle Http Server
 
Oracle Instantis Enterprisetrack
 
Oracle Enterprise Manager Ops Center
 
Oracle Zfs Storage Appliance Kit
 
Oracle Secure Global Desktop
 
Siemens Sinema Server
 
Siemens Sinec Nms
 

What versions are vulnerable to CVE-2021-40438?