CVE-2025-6543—Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability

Vulnerability Name

Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability

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.

Known To Be Used in Ransomware Campaigns?

Ransomware Status:

Unknown

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.

Additional 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

Related News Articles

• Citrix NetScaler Under Active Recon for CVE-2026-3055 (CVSS 9.3) Memory Overread BugMarch 28, 2026
• Citrix Urges Patching Critical NetScaler Flaw Allowing Unauthenticated Data LeaksMarch 24, 2026
• Citrix Patches Three NetScaler Flaws, Confirms Active Exploitation of CVE-2025-7775August 26, 2025
• Over 3,000 NetScaler devices left unpatched against CitrixBleed 2 bugAugust 12, 2025
• Dutch NCSC Confirms Active Exploitation of Citrix NetScaler CVE-2025-6543 in Critical SectorsAugust 12, 2025

Related Weaknesses

• CWE-119