CVE-2025-6543: Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability

Critical severity, CVSS 9.8. Actively exploited: in CISA KEV since 2025-06-30. EPSS: 10.6% chance of exploitation in the next 30 days.

Memory overflow vulnerability leading to unintended control flow and Denial of Service in NetScaler ADC and NetScaler Gateway when configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server

Affected products

• Citrix NetScaler Application Delivery Controller: from 13.1, before 13.1-37.236 (fixed in 13.1-37.236); from 13.1, before 13.1-59.19 (fixed in 13.1-59.19); from 14.1, before 14.1-47.46 (fixed in 14.1-47.46)
• Citrix NetScaler Gateway: from 13.1, before 13.1-59.19 (fixed in 13.1-59.19); from 14.1, before 14.1-47.46 (fixed in 14.1-47.46)

Published 2025-06-25. Last modified 2026-06-17.