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            Singularity vulnerability allowing access to protected files CVE-2018-12021  [EGI-SVG-CVE-2018-12021] 

Date:        2018-07-05 
Updated:     2018-07-09 , 2018-09-20 (advisory placed on wiki)

Affected software and risk

CRITICAL risk vulnerability concerning Singularity

Package : Singularity
CVE ID  : CVE-2018-12021

A vulnerability has been found concerning installations of singularity which support overlayfs, which is the 
default for RedHat Enterprise linux 7 and its derivatives (e.g. SL7) [R 1].

The vulnerability allows a malicious user to escalate privileges and access protected files. 

Actions required/recommended

**UPDATE 2018-07-08**  

The updated version of the singularity RPM (2.5.2) is now available in the EPEL repository. 
Sites should update, urgently if they have not already carried out the mitigation below.

All running resources MUST be either patched or have mitigation
in place or software removed by 2018-07-16  00:00 UTC.

Sites failing to act and/or failing to respond to requests from the EGI CSIRT team risk site suspension. 

Affected software details

This vulnerability has been fixed in Singularity version 2.5.2 

All versions of Singularity including and prior to 2.5.1 are affected.

This vulnerability affects sites running Singularity with RedHat Enterprise linux 7 and its derivatives.

Sites running Singularity with RedHat Enterprise linux 6 and its derivatives are not vulnerable. 


Sites running singularity along with RedHat 7 and its derivatives must disable OverlayFS by replacing 
the `enable overlay` setting in 
`/etc/singularity/singularity.conf` to read `enable overlay = no`.

This was recommended to mitigate a previous singularity vulnerability [R 2], therefore some sites may already 
have mitigation in place. 

The previous version in EPEL, does NOT have overlay_fs disabled by default therefore all sites should ensure 
that overlay_fs is disabled. 

More information

Information on this vulnerability has been released publicly [R 1].

**UPDATE 2018-07-09**

The fixed version, 2.5.2 is now in EPEL production repository.
Sites are recommended to update as soon as possible, urgently if they do not have the mitigation in place.
Component installation information

The rpm patch has been released in EPEL production repository.


** AMBER 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 4]  

Note that this has been updated and the latest version approved by the Operations Management Board in November 2017


[R 1]

[R 2]

[R 3]

[R 4]


SVG was alerted to this vulnerability by Dave Dykstra from OSG 

Yyyy-mm-dd  [EGI-SVG-2018-CVE-2018-12021] 

2018-07-03 SVG alerted to this issue by Dave Dykstra from OSG
2018-07-04 Acknowledgement from the EGI SVG to the reporter
2018-07-04 EGI SVG Risk Assessment completed
2018-07-05 Advisory sent to sites asking sites to mitigate prior to patch being available. 
2018-07-06 (Late) Patch released in EPEL 
2018-07-09 Advisory updated 
2018-07-23 Advisory placed on wiki


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 vulnerabilities"

The risk is that assessed by the group, according to the EGI SVG issue handling procedure [R 4]  
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.   

Others may re-use this information provided they:-

1) Respect the provided TLP classification

2) Credit the EGI Software Vulnerability Group