NetScaler Memory Disclosure Vulnerability - CVE-2026-3055

Citrix NetScaler Memory Disclosure Active Probing

Overview

A critical vulnerability in Citrix NetScaler ADC and Gateway, tracked as CVE-2026-3055, can allow unauthenticated attackers to trigger a memory overread and extract sensitive information from vulnerable systems.

Security reporting indicates active reconnaissance and probing activity, increasing the risk of rapid weaponization and real-world exploitation.

Technical Specifications

Field	Details
Identifier	CVE-2026-3055
Vulnerability Type	Out-of-bounds memory read (memory overread)
Root Cause	Improper input validation in SAML authentication handling
Attack Vector	Crafted HTTP requests (including /cgi/GetAuthMethods)
Exploitable Condition	NetScaler configured as SAML Identity Provider (IdP)
Potential Data Exposure	Session tokens, credentials, internal configuration data

Affected Products

• Citrix NetScaler ADC deployments in vulnerable versions.
• Citrix NetScaler Gateway deployments in vulnerable versions.
• Edge systems exposed to untrusted networks while operating SAML IdP functionality.

Technical Details

• The flaw is a memory disclosure issue caused by out-of-bounds reads during SAML-related request handling.
• Attackers can send crafted HTTP requests to trigger memory overread behavior.
• Public reporting highlights /cgi/GetAuthMethods as a suspicious probing path.
• Leaked memory content may include authentication tokens, credentials, and internal service information.
• Exposure can facilitate follow-on session hijacking and broader compromise of remote access workflows.

Attack Scenario

1. Attacker scans internet-facing assets for reachable NetScaler instances.
2. Systems configured as SAML IdP are identified as higher-value targets.
3. Crafted requests are sent to trigger memory overread behavior.
4. Sensitive memory-resident data is extracted from responses.
5. Stolen tokens/credentials are used for session hijacking and unauthorized access.
6. Adversary uses access footholds for lateral movement and deeper network intrusion.

Impact Assessment

Authentication and Access ImpactInfrastructure Security ImpactData and Operational Impact

Disclosure of tokens and credential material can enable unauthorized access to VPN and remote-access services.

Compromise of edge authentication systems raises risk of broader enterprise intrusion and downstream service compromise.

Successful exploitation can contribute to data-breach risk, incident-response burden, and service reliability concerns.

Mitigation Strategies

• Apply Citrix patches immediately:
  • NetScaler ADC/Gateway 14.1-66.59+
  • NetScaler ADC/Gateway 13.1-62.23+
• Disable SAML IdP mode where not operationally required.
• Restrict external exposure of NetScaler management and authentication interfaces.
• Monitor logs for anomalous requests, especially probes targeting /cgi/GetAuthMethods.
• Enforce network segmentation and strong authentication controls around edge access services.

Resources

Open-Source Reporting

• Urgent Alert: NetScaler bug CVE-2026-3055 probed by attackers could leak sensitive data
• Citrix NetScaler Under Active Recon for CVE-2026-3055 (CVSS 9.3) Memory Overread Bug
• CVE-2026-3055: NetScaler Memory Disclosure Puts SAML-Enabled Edge Devices at Risk
• Citrix NetScaler ADC and Gateway Vulnerabilities (CVE-2026-3055 & CVE-2026-4368) | CyCognito Blog
• NetScaler ADC and NetScaler Gateway Security Bulletin for CVE-2026-3055 and CVE-2026-4368

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Last Updated: March 30, 2026