AMD has disclosed several security issues affecting AMD CPUs. These CPU hardware issues may allow code in a guest VM to infer some active memory content of another VM that is running on the same host. Although these are not vulnerabilities in the XenServer product itself, for the convenience of customers we are providing updates that contain updated AMD microcode and corresponding product code changes to mitigate these CPU hardware issues.
These issues have the following identifiers:
CVE-2024-36350
CVE-2024-36357
Affected Versions
These issues affect XenServer 8.4.
(Note that Citrix Hypervisor 8.2 CU1 is now End of Life (EoL) and so no longer receives security updates or security bulletins.)
Disclaimer
This document is provided on an «as is» basis and does not imply any kind of guarantee or warranty, including the warranties of merchantability or fitness for a particular use. Your use of the information on the document is at your own risk. Cloud Software Group reserves the right to change or update this document at any time. Customers are therefore recommended to always view the latest version of this document directly from the Citrix Knowledge Center.
Details
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
A vulnerability has been identified that impacts Virtual Delivery Agent for Windows used by Citrix Virtual Apps and Desktops and Citrix DaaS.
Affected Versions:
The vulnerability affects the following supported versions of Windows Virtual Delivery Agent for single-session OS:
Current Release (CR)
Citrix Virtual Apps and Desktops versions before 2503
Long Term Service Release (LTSR)
Citrix Virtual Apps and Desktops 2402 LTSR CU2 and earlier versions of 2402 LTSR
Note: Citrix Virtual Apps and Desktops 2203 LTSR is not affected by this vulnerability.
Disclaimer
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.
Details
Virtual Delivery Agent for Windows used by Citrix Virtual Apps and Desktops and Citrix DaaS contains the vulnerability mentioned below:
CVE-ID
Description
Pre-conditions
CWE
CVSSv4
CVE-2025-6759
Local Privilege escalation allows a low-privileged user to gain SYSTEM privileges
Local access to the target system
CWE-269: Improper Privilege Management
CVSS v4.0 Base Score: 6.9(CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
What Customers Should Do
Citrix strongly recommends that customers upgrade their Windows Virtual Delivery Agent for single-session OS to versions that contain the fixes as soon as possible.
Windows Virtual Delivery Agent versions that contain the fixes are:
Current Release (CR)
Citrix Virtual Apps and Desktops 2503 and later versions
The following Updates have been released to address the issues in Citrix Virtual Apps and Desktops 2402 LTSR CU1 and CU2. Customers should ensure they have installed the corresponding cumulative update and then install any applicable updates:
Citrix Virtual Apps and Desktops and Citrix DaaS customers may use Citrix provisioning services or Machine creation services technologies, if applicable, to update their non-persistent Virtual Delivery Agents to the Current Release (CR) Citrix Virtual Apps and Desktops 2503 or later.
Citrix DaaS customers may use VDA Upgrade Service (VUS) to update their Windows persistent Virtual Delivery Agents for Remote PC Access, HDX Plus for Windows 365, and any other persistent or provisioned and dedicated catalogs. Customers are recommended to review the VUS Prerequisites to determine if they can use the VDA Upgrade Service.
Workarounds/ Mitigating Factors
While applying the recommended hotfixes is the preferred solution, customers who are unable to upgrade immediately can apply the following registry change as a temporary workaround on affected systems:
After upgrading NetScaler to build 14.1 47.46 or 13.1 59.19 customers might experience issues with Authentication.This can manifest as a «broken» login page, especially when using authentication methods like DUO configurations based on Radius authentication, SAML, or any Identity Provider (IDP) that relies on custom scripts.
Note : This behavior can possibly be due to the Content Security Policy (CSP) header being enabled by default in this NetScaler build, especially when CSP was not enabled prior to the upgrade.
Lösung
To resolve this issue temporarily, you need to disable the default CSP header on your NetScaler appliance. After disabling, it’s recommended to flush the cache to ensure the changes take effect immediately.
To ensure that your configurations work with CSP , please reach out to the support team so that we can identify the issue and fix it for your configuration.
Steps to Disable CSP Header:
Using Command Line Interface (CLI): Execute the following commands from Netscaler CLI:
set aaa parameter -defaultCSPHeader DISABLED
save ns config
Using Graphical User Interface (GUI):
Step 1: Log in to the NetScaler GUI.
Step 2: Navigate to NetScaler Gateway > Global Settings.
Step 3: Under the «Authentication Settings» section, click on Change authentication AAA settings.
Step 4: On the «Configure AAA Parameters» page, locate the Default CSP Header field. From the dropdown menu, select DISABLED.
Click OK to save the changes.
Post-Configuration Recommendation:
While enabling or disabling the default CSP policy, you are recommended to run the following command in the CLI
flush cache contentgroup loginstaticobjects
After performing the steps above, attempt to access your NetScaler Gateway authentication portal to validate if the issue is resolved.
Zusatz
Bei Fragen und Problemen können Sie sich gerne an Ihren AXACOM Verantwortlichen wenden.
