Overview
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.
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
Key Details
| Property | Value |
|---|---|
| CVE ID | CVE-2025-6543 |
| Vendor / Product | Citrix — NetScaler ADC and Gateway |
| NVD Published | 2025-06-25 |
| NVD Last Modified | 2025-10-24 |
| CVSS 3.1 Score | 9.8 |
| CVSS 3.1 Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Severity | CRITICAL |
| CWE | CWE-119 |
| CISA KEV Added | 2025-06-30 |
| CISA KEV Deadline | 2025-07-21 |
| Known Ransomware Use | No |
CVSS 3.1 Breakdown
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Required Action
CISA BOD 22-01 Deadline: 2025-07-21.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Timeline
| Date | Event |
|---|---|
| 2025-06-30 | Added to CISA Known Exploited Vulnerabilities catalog |
| 2025-07-21 | CISA BOD 22-01 remediation deadline |
References
| Resource | Type |
|---|---|
| NVD — CVE-2025-6543 | Vulnerability Database |
| CISA KEV Catalog Entry | US Government |