CVE-2025-6543

What the flaw is

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.

Description as published by CISA. We have not independently reproduced it.

What CISA requires

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

This deadline is binding on US federal civilian agencies under BOD 22-01. It is not a legal deadline for anyone else, but it is a useful urgency signal — CISA sets it by how actively the flaw is being used, not by CVSS.

Public exploit code

We hold no public exploit references for this CVE. That means our dataset has none — it is not evidence that no exploit exists. CISA has confirmed this vulnerability is being exploited in the wild regardless.

Vendor advisories

• support.citrix.com/support-home/kbsearch/article?articleNumber=CTX694788
• www.netscaler.com/blog/news/netscaler-critical-security-updates-for-cve-2025-6
• nvd.nist.gov/vuln/detail/CVE-2025-6543

Primary sources

• NVD entry — CVSS score, CPE list and references
• CISA KEV catalog — the source for this page
• CVE Record at cve.org