CVE-2023-4966—Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability

Vulnerability Name

Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability

Description

Citrix NetScaler ADC and NetScaler Gateway contain a buffer overflow vulnerability that allows for sensitive information disclosure when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.

Known To Be Used in Ransomware Campaigns?

Ransomware Status:

KNOWN

Action

Apply mitigations and kill all active and persistent sessions per vendor instructions [https://www.netscaler.com/blog/news/cve-2023-4966-critical-security-update-now-available-for-netscaler-adc-and-netscaler-gateway/] OR discontinue use of the product if mitigations are unavailable.

Additional Notes

• https://www.netscaler.com/blog/news/cve-2023-4966-critical-security-update-now-available-for-netscaler-adc-and-netscaler-gateway/, https://support.citrix.com/article/CTX579459/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20234966-and-cve20234967
• https://nvd.nist.gov/vuln/detail/CVE-2023-4966

Related News Articles

• Citrix NetScaler Under Active Recon for CVE-2026-3055 (CVSS 9.3) Memory Overread BugMarch 28, 2026
• Citrix urges admins to patch NetScaler flaws as soon as possibleMarch 25, 2026
• Citrix Urges Patching Critical NetScaler Flaw Allowing Unauthenticated Data LeaksMarch 24, 2026
• CISA tags Citrix Bleed 2 as exploited, gives agencies a day to patchJuly 11, 2025
• CISA Adds Citrix NetScaler CVE-2025-5777 to KEV Catalog as Active Exploits Target EnterprisesJuly 11, 2025

Related Weaknesses

• CWE-119