CVE-2025-7775 in NetScaler ADC (CitrixDeelb)
Summary
by MITRE • 08/26/2025
Memory overflow vulnerability leading to Remote Code Execution and/or Denial of Service in NetScaler ADC and NetScaler Gateway when NetScaler is configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server
(OR)
NetScaler ADC and NetScaler Gateway 13.1, 14.1, 13.1-FIPS and NDcPP: LB virtual servers of type (HTTP, SSL or HTTP_QUIC) bound with IPv6 services or servicegroups bound with IPv6 servers
(OR)
NetScaler ADC and NetScaler Gateway 13.1, 14.1, 13.1-FIPS and NDcPP: LB virtual servers of type (HTTP, SSL or HTTP_QUIC) bound with DBS IPv6 services or servicegroups bound with IPv6 DBS servers
(OR)
CR virtual server with type HDX
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Analysis
by VulDB Data Team • 09/02/2025
This memory overflow vulnerability in Citrix NetScaler ADC and NetScaler Gateway represents a critical security flaw that can lead to remote code execution or denial of service conditions. The vulnerability specifically affects systems configured as gateways including VPN virtual servers, ICA Proxy, CVPN, RDP Proxy, and AAA virtual servers. Additionally, it impacts load balancing virtual servers of types HTTP, SSL, or HTTP_QUIC when bound with IPv6 services or service groups containing IPv6 servers, as well as DBS IPv6 services or service groups with IPv6 DBS servers. The flaw manifests when the system processes certain network traffic patterns involving IPv6 addressing, creating potential attack vectors for malicious actors to exploit. The vulnerability stems from insufficient input validation and memory management within the NetScaler's processing pipeline for IPv6 traffic, particularly when handling complex service group configurations.
The technical implementation of this vulnerability involves improper memory allocation and handling during processing of IPv6 network packets within the NetScaler's load balancing and gateway components. When the system encounters specific combinations of IPv6 addresses in service groups or virtual server configurations, it fails to properly validate the memory boundaries required for processing these network requests. This leads to buffer overflows that can be leveraged by attackers to execute arbitrary code on the target system or cause service disruption through denial of service conditions. The vulnerability is particularly concerning because it affects core networking functionality within the NetScaler platform, potentially allowing attackers to gain unauthorized access to the underlying infrastructure or disrupt critical network services. The attack surface expands significantly when considering the various virtual server types and service configurations that can trigger the memory overflow condition.
The operational impact of this vulnerability extends across enterprise network infrastructures that rely on Citrix NetScaler for critical services including secure remote access, load balancing, and application delivery. Organizations using NetScaler ADC or Gateway in production environments with IPv6 configurations face potential compromise of their network security posture, as successful exploitation could enable attackers to establish persistent access to internal networks through VPN connections or gain control over load balancing services. The vulnerability affects multiple versions including 13.1, 14.1, 13.1-FIPS, and NDcPP releases, indicating a widespread impact across the Citrix NetScaler product line. This creates significant challenges for security teams who must assess and remediate systems across various deployment scenarios, from traditional VPN gateways to modern application delivery controllers. The potential for remote code execution makes this vulnerability particularly dangerous for organizations with limited network segmentation or those that do not maintain robust monitoring of their NetScaler appliances.
Organizations should prioritize immediate remediation through official Citrix security patches and updates, while implementing network segmentation to limit exposure of vulnerable NetScaler appliances to untrusted networks. Security monitoring should be enhanced to detect unusual network traffic patterns that might indicate exploitation attempts, particularly around IPv6 service group configurations. The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and maps to ATT&CK techniques including T1059 for command and control execution and T1499 for network denial of service. Network administrators should also consider implementing temporary workarounds such as disabling IPv6 service configurations on affected virtual servers until proper patches are deployed. The remediation process should include comprehensive testing of patched systems to ensure no regression in functionality while maintaining the security posture against this memory overflow threat. Regular vulnerability assessments should be conducted to identify any other potential configurations that might be susceptible to similar memory handling issues within the NetScaler platform or related network infrastructure components.