What Customers Should Do  

We have pushed updates to both the Early Access and Normal update channels of XenServer 8.4.  We recommend that customers update to the latest version from their chosen channel following the instructions at https://docs.xenserver.com/en-us/xenserver/8/update 

What Citrix is Doing   

We are notifying customers and channel partners about this potential security issue through the publication of this security bulletin on the Citrix Knowledge Center at https://support.citrix.com/support-home/topic-article-list?trendingCategory=20&trendingTopicName=Security%20Bulletin 

Obtaining Support on This Issue  

If you require technical assistance with this issue, please contact Citrix Technical Support. Contact details for Citrix Technical Support are available at https://www.citrix.com/support 

Subscribe to Receive Alerts  

Citrix strongly recommends that all customers subscribe to receive alerts when a security bulletin is created or modified at https://support.citrix.com/wolken-support/view/aboutsupport/my-support-alerts 

Reporting Security Vulnerabilities to Citrix  

Citrix welcomes input regarding the security of its products and considers any and all potential vulnerabilities seriously. For details on our vulnerability response process and guidance on how to report security-related issues to Citrix, please see the following webpage: https://www.cloud.com/trust-center/support  

Change Log

The information on this page is being provided to you on an "AS IS" and "AS-AVAILABLE" basis. The issues described on this page may or may not impact your system(s). Cloud Software Group, Inc. and its subsidiaries (collectively, "Cloud SG") make no representations, warranties, or guarantees as to the information contained herein. ANY AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY, NON-INFRINGEMENT AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. BY ACCESSING THIS PAGE, YOU ACKNOWLEDGE THAT CLOUD SG SHALL IN NO EVENT BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES THAT ARISE OUT OF YOUR USE OR FAILURE TO USE THE INFORMATION CONTAINED HEREIN. Cloud SG reserves the right to change or update the information on this page at any time. We accordingly recommend that you always view the latest version of this page. The information contained herein is being provided to you under the terms of your applicable customer agreement with Cloud SG, and may be used only for the purposes contemplated by such agreement. If you do not have such an agreement with Cloud SG, this information is provided under the cloud.com Terms of Use, and may be used only for the purposes contemplated by such Terms of Use. 

Severity: Medium 

Description of Problem  

An issue has been identified in XenServer 8.4 that may allow privileged code in a guest VM to cause the host to become slow or unresponsive to management operations. This issue has the following identifier:  

• CVE-2025-58151 

A further issue has been identified in XenServer 8.4 that may allow code in a guest VM process to infer in-memory data of a different process running within that same VM. This issue has the following identifier: 

• CVE-2026-23553 

Affected Versions  

These issues affect XenServer 8.4.