Archive: Vulnerability in XenServer Could Result in Authentication Bypass

  • CTX123456
  • Created On  Feb 02, 2010
  • Updated On  Mar 10, 2012
  • Security Bulletin
This article is no longer maintained, its content refers to a discontinued product and may be out of date. Refer to the Discontinued Product Lifecycle or Active Citrix Product pages for more information on support schedules.

Severity: High

Description of Problem

A vulnerability has been discovered in XenServer that, when triggered, could allow a subset of Xen API (XAPI) calls to be executed without proper authentication.

This vulnerability affects the following versions of XenServer only:

• XenServer 5.0 Update 3 and earlier

• XenServer 5.5

Customers running XenServer 5.5 Update 1 or later, are not affected by this vulnerability.

What Customers Should Do

A hotfix has been released to address this issue. Citrix recommends that customers using affected versions of XenServer install this hotfix, which can be downloaded from the following locations:

Citrix XenServer 5.0:

Citrix XenServer 5.5:

This vulnerability is addressed in XenServer 5.5 Update 1, which is available at

What Citrix Is Doing

Citrix is notifying customers and channel partners about this potential security issue. This article is also available from the Citrix Knowledge Center at

Obtaining Support on this Issue

If you require technical assistance with this issue, please contact Citrix Technical Support. Information for contacting Citrix Technical Support is available at

Reporting Security Vulnerabilities to Citrix

Citrix welcomes input regarding the security of its products and considers any and all potential vulnerabilities seriously. If you would like to report a security issue to Citrix, please compose an e-mail to containing the exact version of the product in which the vulnerability was found and the steps needed to reproduce the vulnerability.

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