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Main page Software Security Checklist Issue Handling Advisories Notes On Risk Advisory Template More


Title:       EGI SVG 'ADVISORY' [TLP:WHITE] HIGH risk Linux Kernel release fixing various software vulnerabilities 

Date:        2021-01-06
Updated:     2021-03-22, 2021-04-06

Affected software and risk

Various vulnerabilities concerning the Linux kernel including 2 which are 'HIGH' risk 

Package : Linux Kernel
CVE ID  : CVE-2020-25211, CVE-2020-29661
Bug ID  : Red Hat Bugzilla 1877571

CVE-2020-25211 A buffer overflow vulnerability has been announced by RedHat which may allow a local user 
to crash the system, compromise data confidentiality and the integrity of the system. [R 1] [R 2] [R 3] [R 4]

Additionally, this Advisory acts as an 'UPDATE' to the advisory sent on 6th January 2021 concerning this 
vulnerability and asking sites to mitigate. 

CVE-2020-29661 A locking vulnerability was found in the tty subsystem of the Linux kernel in drivers/tty/tty_jobctrl.c. 
This flaw allows a local attacker to possibly corrupt memory or escalate privileges. 
The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. [R 7]

Other vulnerabilities may also have been fixed in this release.

Actions required/recommended

Updated packages are available for RHEL 7 and 8 and CentOS 7 & 8

Sites which have not updated already should update as soon as possible.

Component installation information

Sites should see [R 4] [R 7] 

Mitigation for CVE-2020-25211

Ensure that unprivileged _network_ namespaces are disabled, if they are not required. 

Note that unprivileged user/network namespaces are enabled by default in RHEL 8 but not in RHEL 7 and derivatives. 

If sites need to have unprivileged _network_ namespaces enabled they should consider the mitigation in [R 4], [R 5]

More information

There is the possibility that one of these vulnerabilities may be elevated to 'CRITICAL' 
if a public exploit is released which allows easy exploitation.

In general, the EGI SVG recommends disabling _network_ namespaces whenever possible, as many vulnerabilities 
are only exploitable if network namespaces are enabled. 


** WHITE information - Unlimited 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 to fully handle vulnerabilities in the EOSC-hub era. 


[R 1]

[R 2]

[R 3]  

[R 4]

[R 5]

[R 6]

[R 7]


SVG was alerted to both the vulnerabilities specifically mentioned by Vincent Brillault 

Yyyy-mm-dd  [EGI-SVG-2021-CVE-2020-25211] 

2021-01-04 SVG alerted to CVE-2020-25211 by Vincent Brillault
2021-01-04 Acknowledgement from the EGI SVG to the reporter
2021-01-04 Investigation of vulnerability and relevance to EGI carried out
2021-01-05 EGI SVG Risk Assessment completed
2021-01-06 Advisory sent to sites to mitigate CVE-2020-25211
2021-02-17 SVG alerted to CVE-2020-29661 by Vincent Brillault
2021-03-16 RedHat Kernel release which fixes various vulnerabilities, including CVE-2020-25211, CVE-2020-29661
2021-03-22 Advisory/update issued as fix available for RHEL 7, CentOS 7, RHEL 8, CentOS 8 for at least 2 vulnerabilities.
2021-04-06 Advisory placed on the EGI SVG 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 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 and the services in the EOSC-hub catalogue.

On behalf of the EGI SVG,