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[ CVE-2025-6543 · Published 25 Jun 2025 ]

Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability

Exploited · CISA KEV CVSS 9.8 EPSS 11%No fix listed yet

[ Why it matters ]Priority signals

  • Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2025-06-30
  • EPSS: 11% chance of exploitation in the next 30 days (higher than 96% of CVEs)
  • Critical severity: CVSS 9.8

[ Description ]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

CISA: 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.

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 21 Jul 2025): Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References