CVE-2025-6543 Citrix NetScaler ADC and Gateway Buffer Overflow
Attackers can cause memory overflow leading to denial of service or unintended control flow in NetScaler Gateway or AAA virtual servers.
- Exploited in the wild
- Since 30 Jun 2025
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-6543?
CVE-2025-6543 is a critical memory corruption vulnerability in NetScaler ADC, published on 25 Jun 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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
Weakness: CWE-119
Which versions are affected by CVE-2025-6543?
It affects 2 products.
Products include Citrix NetScaler ADC, Citrix Netscaler Gateway.
How do I fix CVE-2025-6543?
No fix has been published for CVE-2025-6543 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 21 Jul 2025.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2025-6543 being exploited?
Yes. Attackers have exploited CVE-2025-6543 in the wild since at least 30 Jun 2025.
Public exploit code: 3 proofs of concept on GitHub.
Other vulnerabilities in NetScaler ADC
- CVE-2023-3519 Citrix NetScaler ADC and NetScaler Gateway Code Injection
- CVE-2026-88771 Citrix NetScaler Improper Input Validation
- CVE-2026-88772 Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer
- CVE-2023-4966 Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow
- CVE-2026-19490 Citrix NetScaler Authentication Bypass Using an Alternate Path or Channel
Sources
Also known as GHSA-9gqr-6728-fpv3.