CVE-2025-6543: Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability
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.
| Vendor | Citrix |
|---|---|
| Product | NetScaler ADC and Gateway |
| Date added to KEV | 2025-06-30 |
| Due date (BOD 22-01) | 2025-07-21 |
| Known ransomware campaign use | Unknown |
| CWE | CWE-119 |
| Required action | Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. |
What to do
- Identify every instance of Citrix NetScaler ADC and Gateway in your environment (asset inventory, EDR, vulnerability scanner).
- Apply CISA's required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- Federal civilian agencies must act by 2025-07-21 under BOD 22-01; other organizations can use the same date as a target.
- Check the vendor advisory and NVD entry linked below for affected versions, then record the fix in your change log.
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Sources
- NVD entry for CVE-2025-6543 (severity scores, if any, live there)
- CISA KEV catalog entry
- 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