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26 September 2019

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             AUSCERT External Security Bulletin Redistribution

   Multiple Vulnerabilities in Citrix License Server for Windows and VPX
                             26 September 2019


        AusCERT Security Bulletin Summary

Product:           Citrix License Server
Publisher:         Citrix
Operating System:  Windows
Impact/Access:     Execute Arbitrary Code/Commands -- Remote/Unauthenticated
                   Denial of Service               -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-20034 CVE-2018-20033 CVE-2018-20032

Reference:         ESB-2019.2582

Original Bulletin: 

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Multiple Vulnerabilities in Citrix License Server for Windows and VPX

Reference: CTX261963
Category : Medium
Created  : 25 Sep 2019
Modified : 25 Sep 2019

Applicable Products

  o Licensing

Description of Problem

Multiple Denial-of-Service vulnerabilities have been identified in Citrix
License Server for Windows and VPX that, when exploited, could result in an
attacker being able to force the vendor service to shutdown. These
vulnerabilities have been assigned the following CVE numbers:

o CVE-2018-20031: A Denial of Service vulnerability in FlexNet Publisher
version and earlier

o CVE-2018-20032: A Denial of Service vulnerability in FlexNet Publisher
version and earlier

o CVE-2018-20033: A Remote Code Execution vulnerability in FlexNet Publisher
version and earlier

o CVE-2018-20034: A Denial of Service vulnerability in FlexNet Publisher
version and earlier

This vulnerability affects the following Citrix License Server versions:

o Citrix License Server for Windows earlier than and including Build

o Citrix License Server VPX all supported versions.

Mitigating Factors

If access to admin console is restricted to trusted network the risk is

Security considerations for the admin console interface can be found at the
following URL:


Under security considerations

"Configure the License Server environment so that only authorized
administrators on a trusted network can access the Licensing Administration
Console port. You achieve this outcome by using an appropriately configured
network or host-based firewall."

What Customers Should Do

The vulnerabilities have been addressed in the following version:

o Citrix License Server for Windows version 11.16.3 build 28000 and newer.

Customers with Citrix License Server VPX will need to deploy the Windows
version for the fix.

Citrix recommends that customers upgrade their Citrix License Server
deployments to this version or later. The updates can be obtained from the
following location:



|Date                                  |Change                                |
|25th September 2019                   |Initial Publication                   |

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