Critical Citrix VDA Vulnerability Allows Attackers to Gain SYSTEM-Level Access on Windows

A high-severity security vulnerability affecting Citrix Virtual Apps and Desktops and Citrix DaaS systems worldwide.

The vulnerability, designated as CVE-2025-6759, enables local attackers with low-level privileges to escalate their access to SYSTEM-level privileges on affected Windows Virtual Delivery Agent installations.

With a CVSS v4.0 base score of 7.3, this security vulnerability poses significant risks to enterprise environments relying on Citrix’s virtualization infrastructure.

The vulnerability stems from improper privilege management within the Windows Virtual Delivery Agent component, classified under CWE-269.

Security researchers have identified that attackers who already possess local access to target systems can exploit this weakness to gain complete administrative control.

The attack vector requires high attack complexity but no user interaction, making it particularly concerning for environments where multiple users share virtualized resources.

The vulnerability specifically impacts single-session Windows Virtual Delivery Agent installations, which are commonly deployed in enterprise virtual desktop infrastructure (VDI) environments.

Once exploited, attackers can execute arbitrary code with SYSTEM privileges, potentially compromising sensitive data, installing malware, or establishing persistent access to corporate networks.

The vulnerability’s local nature means attackers must first gain initial access to the target system through other means, but once present, they can easily escalate their privileges.

Critical Citrix VDA Vulnerability

The security vulnerability affects multiple Citrix product versions across different release tracks. Current Release (CR) versions of Citrix Virtual Apps and Desktops prior to version 2503 are vulnerable to this privilege escalation attack.

Additionally, Long Term Service Release (LTSR) versions including Citrix Virtual Apps and Desktops 2402 LTSR CU2 and all earlier versions within the 2402 LTSR branch are affected.

However, organizations using Citrix Virtual Apps and Desktops 2203 LTSR can breathe easier, as this version remains unaffected by the vulnerability.

Cloud Software Group has released comprehensive fixes for affected systems, including Current Release version 2503 and later versions for CR users.

LTSR customers have access to specific updates including Citrix Virtual Apps and Desktops 2402 LTSR CU1 Update 1 and CU2 Update 1, which directly address the security issue.

Organizations can leverage existing Citrix technologies to streamline the update process. Citrix DaaS customers can utilize the VDA Upgrade Service (VUS) for persistent Virtual Delivery Agents, while provisioning services and Machine creation services can help update non-persistent agents to the patched versions.

Recommendations

According to Report, Cloud Software Group acknowledges that some organizations may require temporary measures Citrix Virtual Apps.

A registry-based workaround is available for systems that cannot be immediately updated.

Administrators can disable the vulnerable component by setting the “Enabled” value to “00000000” in the registry key “HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\CtxExceptionHandler”.

Organizations can deploy this workaround using Citrix Workspace Environment Management for large-scale implementations.

However, Cloud Software Group strongly emphasizes that this workaround should only serve as a temporary measure while planning full system updates.

The vulnerability discovery involved collaboration between Cloud Software Group and external security researchers, including Timm Lippert and Christopher Beckmann from SySS GmbH, as well as Brandon Fisher from Rapid7.

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