EGI SVG Advisories


Title:       EGI SVG 'ADVISORY' [TLP:WHITE] HIGH risk CVE-2021-40438 / 
             httpd mod_proxy vulnerability [EGI-SVG-CVE-2021-40438]  

Date:        2021-11-01

Affected software and risk

HIGH risk vulnerability concerning httpd mod_proxy.

Package : httpd
CVE ID  : CVE-2021-40438
Bug ID  : 2005117

A Server-Side Request Forgery (SSRF) flaw was found in mod_proxy of httpd. 
This flaw allows a remote, unauthenticated attacker to make the httpd server 
forward requests to an arbitrary server. The attacker could get, modify, or 
delete resources on other services that may be behind a firewall and 
inaccessible otherwise. The impact of this flaw varies based on what services 
and resources are available on the httpd network. [R 1], [R 2]

Actions required/recommended

Sites should update as soon as possible, updated packages are available.

Component installation information

Sites running RHEL 8 and RHEL 7 should see [R 1]

Sites running CentOS should also see [R 1]

Sites running Debian should see [R 3] 

Sites running Ubuntu should see [R 4]

Sites running Scientific Linux should see [R 5]

More information

For more information see [R 1]


** WHITE information - Limited distribution
 - see for
   distribution restrictions **

Minor updates may be made without re-distribution to the sites


Comments or questions should be sent to svg-rat  at

If you find or become aware of another vulnerability which is relevant to EGI 
you may report it by e-mail to  

report-vulnerability at

the EGI Software Vulnerability Group will take a look according to the procedure 
defined in [R 6]. 

Note that this is undergoing revision.


[R 1]

[R 2] 

[R 3]

[R 4] 

[R 5] 

[R 6]


SVG was alerted to this vulnerability by Mischa Salle

Yyyy-mm-dd  [EGI-SVG-CVE-2021-40438] 

2021-10-21 SVG alerted to this issue by Mischa Salle of the SVG
2021-10-21 Acknowledgement from the EGI SVG to the reporter
2021-10--- Investigation of vulnerability and relevance to EGI carried out 
2021-10-28 EGI SVG Risk Assessment completed
2021-11-01 Advisory/Alert sent to sites
2022-07-08 Placed on public web page


This advisory has been prepared as part of the effort to fulfil EGI SVG's 
purpose "To minimize the risk to the EGI infrastructure arising from software 

The risk is that assessed by the group, according to the EGI SVG issue handling 
procedure [R 6] in the context of how the software is used in the EGI 
infrastructure. It is the opinion of the group, we do not guarantee it to be 
correct. The risk may also be higher or lower in other deployments depending on 
how the software is used.   

This advisory is subject to the Creative commons licence and 
the EGI Software Vulnerability Group must be credited. 

Note that the SVG issue handling procedure is currently under review, to take 
account of the increasing inhomogeneity of the EGI infrastructure. 

On behalf of the EGI SVG,