CVE-2025-6543 — Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability
CVE-2025-6543: Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability
CISA Known Exploited Vulnerability (KEV)
| Vendor / project | Citrix |
| Product | NetScaler ADC and Gateway |
| Date added | 2025-06-30 |
| Due date | 2025-07-21 |
| Ransomware campaign use | Unknown |
Description
Citrix NetScaler ADC and Gateway contain a buffer overflow vulnerability leading to unintended control flow and Denial of Service. NetScaler must be configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.
Required action (CISA)
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Notes
https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX694788 ; https://www.netscaler.com/blog/news/netscaler-critical-security-updates-for-cve-2025-6543-and-cve-2025-5777/ ; https://nvd.nist.gov/vuln/detail/CVE-2025-6543
References
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-6543
- KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog