CVE-2026-3055 Citrix NetScaler Out-of-Bounds Read Vulnerability

Summary

March 30, 2026, the Cybersecurity and Infrastructure Security Agency (CISA) has added a new vulnerability to its Known Exploited Vulnerabilities (KEV) Catalog due to confirmed active exploitation.

The vulnerability added:
• CVE-2026-3055 – Citrix NetScaler Out-of-Bounds Read Vulnerability

CISA warns that this type of vulnerability is a common attack vector and poses significant risk to enterprise and government environments.

Research Source

According to CISA, the KEV Catalog is a living list of actively exploited vulnerabilities that organizations should prioritize for remediation.

The update is part of Binding Operational Directive (BOD) 22-01, which mandates U.S. federal agencies to patch vulnerabilities within defined timelines.

Technical Details

Vulnerability Type:
• Out-of-Bounds Read

Affected System:
• Citrix NetScaler

Out-of-bounds read vulnerabilities may allow attackers to:

• Access unintended memory locations
• Potentially expose sensitive data
• Assist in further exploitation or chaining attacks

Such flaws are frequently used in initial access or reconnaissance phases of cyberattacks.

Observed Attack Activity

Threat Activity
• Active exploitation confirmed by CISA

Attack Use Cases
• Information disclosure
• Reconnaissance of target systems
• Potential chaining with other vulnerabilities

Threat Actors
• Not specifically attributed
• Likely used by opportunistic attackers and advanced threat groups

Impact

Exploitation of this vulnerability may lead to:

• Exposure of sensitive system memory
• Increased risk of follow-on attacks
• Potential compromise of network edge devices

Since Citrix NetScaler is commonly used as a network edge and access control device, exploitation could provide attackers with a critical foothold into enterprise networks.

Mitigation

CISA strongly recommends:

Apply vendor patches immediately for CVE-2026-3055
Prioritize KEV-listed vulnerabilities in patch management programs
Monitor systems for signs of exploitation
Review access logs for unusual activity on Citrix devices
Implement network segmentation and least privilege access

Organizations should integrate KEV remediation into their vulnerability management lifecycle.

References
• https://www.cisa.gov/news-events/alerts/2026/03/30/cisa-adds-one-known-exploited-vulnerability-catalog