Citrix

Security Advisory

Multiple Critical Vulnerabilities in Citrix NetScaler ADC/Gateway 

Security Advisory: Multiple vulnerabilities have been discovered in NetScaler ADC (formerly Citrix ADC) and NetScaler Gateway One Actively Exploited in Wild .

Citrix credited Jimi Sebree of Horizon3.ai, Jonathan Hetzer of Schramm & Partnerfor and Francois Hammerli for discovering and reporting the vulnerabilities.

Severity Critical 
CVSS Score 9.2 
CVEs CVE-2025-7775, CVE-2025-7776, CVE-2025-8424 
POC Available No 
Actively Exploited Yes 
Exploited in Wild Yes 
Advisory Version 1.0 

Overview 
A critical zero-day vulnerability, tracked as CVE-2025-7775, puts over 28,200 Citrix instances at risk worldwide.

This flaw allows attackers to run malicious code on affected systems without authentication. The issue is actively being exploited in the wild and immediate action is needed to secure systems.  Another two flaws were fixed in the latest updates.  

Vulnerability Name CVE ID Product Affected Severity 
Memory overflow vulnerability leading to RCE CVE-2025-7775 NetScaler ADC & Gateway 9.2 
Memory overflow vulnerability leading to unpredictable behavior CVE-2025-7776 NetScaler ADC & Gateway 8.8 
Improper access control on the NetScaler Management Interface CVE-2025-8424 NetScaler ADC & Gateway 8.7 

Technical Summary 

The NetScaler ADC and NetScaler Gateway appliances are affected by multiple critical vulnerabilities that pose significant risks ranging from Remote Code Execution (RCE) and Denial of Service (DoS) to improper access control.

These include memory overflow flaws in configurations such as VPN virtual servers, load balancing virtual servers using IPv6 or DBS IPv6 services, and misconfigurations involving PCoIP profiles. Additionally, the management interface is exposed due to weak access control mechanisms, which could allow unauthorized administrative access if attackers reach key management IP addresses like NSIP or SNIP. CISA has added one vulnerability (CVE-2025-7775) to its Known Exploited Vulnerabilities (KEV) Catalog and strongly urges organizations to apply patches immediately to prevent active exploitation. 

CVE ID System Affected  Vulnerability Details Impact 
CVE-2025-7775  NetScaler ADC & Gateway  A critical memory overflow vulnerability in NetScaler ADC and Gateway that can lead to Remote Code Execution or DoS when configured as a Gateway (e.g., VPN, ICA Proxy, CVPN, RDP Proxy), AAA virtual server, or LB virtual server using IPv6 or DBS IPv6 services including CR virtual servers of type HDX. Remote Code Execution or DoS  
CVE-2025-7776  NetScaler ADC & Gateway A memory overflow vulnerability under analysis, currently known to cause unpredictable system behavior and potential DoS when a PCoIP Profile is bound to a Gateway-configured NetScaler instance (VPN, ICA Proxy, CVPN, RDP Proxy), Erroneous behavior and DoS 
CVE-2025-8424 NetScaler ADC & Gateway An improper access control vulnerability on the NetScaler Management Interface, allowing unauthorized access when attackers can reach management IPs (NSIP, Cluster Management IP, local GSLB Site IP, or SNIP with Management Access), affecting NetScaler ADC and Gateway appliances. Unauthorized access 

Recommendations 

NetScaler ADC and NetScaler Gateway to install the relevant updated versions as soon as possible.  

  • NetScaler ADC and NetScaler Gateway 14.1-47.48 and later releases 
  • NetScaler ADC and NetScaler Gateway 13.1-59.22 and later releases of 13.1 
  • NetScaler ADC 13.1-FIPS and 13.1-NDcPP 13.1-37.241 and later releases of 13.1-FIPS and 13.1-NDcPP 
  • NetScaler ADC 12.1-FIPS and 12.1-NDcPP 12.1-55.330 and later releases of 12.1-FIPS and 12.1-NDcPP 

Here are some other recommendations below 

  • Monitor systems for unusual activity or unauthorized changes. 
  • Limit access to Citrix instances from untrusted networks. 
  • Use firewalls to block suspicious traffic targeting Citrix instances. 

Conclusion: 

Combined with additional high-severity vulnerabilities the overall threat landscape demands immediate attention. Organizations are strongly urged to apply the latest patches, restrict access to management interfaces and closely monitor for signs of compromise. Delayed action could result in significant operational and security impacts. 

The active exploitation of CVE-2025-7775 highlights a critical security threat affecting multiple NetScaler ADC and Gateway instances globally. This zero-day confirmed exploitation in the wild poses a severe risk of Remote Code Execution and service disruption.

References: 

  

Security Advisory

Citrix NetScaler ADC/Gateway Vulnerability Exploited in the Wild (CVE-2025-6543) 

Summary : Security Advisory;

Citrix is warning that a vulnerability in NetScaler appliances tracked as CVE-2025-6543 is being actively exploited in the wild, causing devices to enter a denial of service condition.

The flaw impacts NetScaler ADC and NetScaler Gateway versions 14.1 before 14.1-47.46, 13.1 before 13.1-59.19, and NetScaler ADC 13.1-FIPS and NDcPP before 13.1-37.236-FIPS and NDcPP.

OEM Citrix 
Severity Critical 
CVSS Score 9.2 
CVEs CVE-2025-6543 
POC Available No 
Actively Exploited Yes 
Exploited in Wild Yes 
Advisory Version 1.0 

Overview 

A critical memory overflow vulnerability, CVE-2025-6543, has been discovered in NetScaler ADC and NetScaler Gateway products, potentially leading to denial-of-service and unintended control flow. The issue affects deployments configured as Gateway services. Active exploitation in the wild has been reported. 

Vulnerability Name CVE ID Product Affected Severity Fixed Version 
​Memory overflow vulnerability  CVE-2025-6543 NetScaler ADC and NetScaler Gateway  Critical  14.1-47.46 / 13.1-59.19 / 13.1-37.236 

Technical Summary 

CVE-2025-6543 is a memory overflow vulnerability in NetScaler ADC and Gateway products that can result in denial-of-service (DoS) or arbitrary control flow, particularly when the system is configured as a Gateway or AAA virtual server.

The flaw stems from improper restriction of operations within memory buffer bounds (CWE-119). This vulnerability has been exploited in real-world attacks. 

CVE ID System Affected  Vulnerability Details Impact 
  CVE-2025-6543 NetScaler ADC & Gateway 14.1 before 14.1-47.46, 13.1 before 13.1-59.19 NetScaler ADC 13.1-FIPS and NDcPP before 13.1-37.236-FIPS and NDcPP Memory overflow due to improper memory boundary restrictions when configured as Gateway or AAA virtual servers  Denial-of-Service and Unintended control flow 

Remediation: 

  • Immediate Action: Affected customers are strongly advised to upgrade to the fixed versions: 
Product Version Recommended Fixed Build 
NetScaler ADC / Gateway 14.1 14.1-47.46 or later 
NetScaler ADC / Gateway 13.1 13.1-59.19 or later 
NetScaler ADC 13.1-FIPS / NDcPP 13.1-37.236 or later 

Note: Versions 12.1 and 13.0 are End-of-Life (EOL) and remain vulnerable. These should be replaced with supported, patched builds. 

Customers using FIPS or NDcPP variants should contact Citrix Support directly for access to the fixed builds. 

Conclusion: 
CVE-2025-6543 represents a highly critical risk to organizations utilizing NetScaler Gateway or ADC for secure access and application delivery.

Organizations still using outdated or end-of-life (EOL) versions are especially vulnerable and should prioritize upgrading to supported builds. 

This flaw follows a pattern of severe vulnerabilities affecting NetScaler products, including the recently disclosed CVE-2025-5777 (CVSS score: 9.3), which also posed a significant threat to enterprise infrastructure.

Together these issues highlight the urgent need for timely patching, continuous monitoring, and defense-in-depth strategies to safeguard critical network assets. 

With both flaws being critical bugs, administrators are advised to apply the latest patches from Citrix as soon as possible.

Companies should also monitor their NetScaler instances for unusual user sessions, abnormal behavior, and to review access controls.

References: 

Scroll to top