CVE-2025-7776 in NetScaler ADC
Summary
by MITRE • 08/26/2025
Memory overflow vulnerability leading to unpredictable or erroneous behavior and Denial of Service in NetScaler ADC and NetScaler Gateway when NetScaler is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) with PCoIP Profile bounded to it
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Analysis
by VulDB Data Team • 09/04/2025
The vulnerability identified as CVE-2025-7776 represents a critical memory overflow condition within Citrix NetScaler ADC and NetScaler Gateway appliances when operating in gateway mode configurations. This flaw specifically manifests when the system is configured as a VPN virtual server, ICA Proxy, CVPN, or RDP Proxy environment with PCoIP profiles bound to these services. The vulnerability resides in the handling of network traffic processing within the gateway components, where insufficient bounds checking allows malicious input to cause memory corruption during normal operational procedures.
The technical implementation of this vulnerability stems from inadequate input validation within the PCoIP profile processing pipeline of the NetScaler gateway services. When legitimate or malicious network requests are processed through the configured gateway virtual servers, the system fails to properly validate the size and structure of incoming data packets before allocating memory buffers. This memory overflow condition can occur during the parsing of PCoIP protocol-specific headers or data segments, leading to stack or heap corruption that results in unpredictable application behavior. The flaw operates at the network protocol processing layer where the system attempts to handle PCoIP traffic flows while maintaining state information for the gateway services.
From an operational impact perspective, this vulnerability creates significant risk for organizations relying on Citrix NetScaler solutions for remote access and application delivery. The memory overflow condition can lead to complete service disruption through denial of service scenarios where the affected NetScaler appliance becomes unresponsive or crashes entirely. Additionally, the unpredictable behavior resulting from memory corruption may allow for potential privilege escalation or information disclosure attacks depending on the specific memory layout and execution context. Organizations utilizing this configuration may experience extended downtime for critical remote access services, potentially affecting business continuity and user productivity. The vulnerability affects all versions of NetScaler ADC and NetScaler Gateway that support PCoIP profile binding in gateway mode configurations, making it particularly concerning for enterprises with widespread Citrix deployments.
Mitigation strategies for CVE-2025-7776 should prioritize immediate patch application from Citrix security advisories, as this vulnerability requires vendor-provided fixes to address the underlying memory handling flaws. Network administrators should implement temporary traffic filtering measures to restrict PCoIP protocol access until patches are deployed, though this may impact legitimate business operations requiring such connectivity. Monitoring solutions should be enhanced to detect unusual memory consumption patterns or service disruptions that may indicate exploitation attempts. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow and CWE-122 Heap-based Buffer Overflow classifications, representing a classic memory safety issue that violates secure coding practices. From an attack framework perspective, this vulnerability maps to ATT&CK technique T1499.004 for network denial of service and potentially T1071.004 for application layer protocol usage, making it a critical target for both automated exploitation tools and targeted advanced persistent threat actors seeking to disrupt enterprise remote access infrastructure.