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[ CVE-2023-4966 · Published 10 Oct 2023 ]

Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability

Exploited · CISA KEV CVSS 7.5 EPSS 100%No fix listed yet

[ Why it matters ]Priority signals

  • Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2023-10-18
  • Known to be used in ransomware campaigns
  • EPSS: 100% chance of exploitation in the next 30 days (higher than 100% of CVEs)

[ Description ]Official description

Sensitive information disclosure in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA  virtual server.

CISA: Citrix NetScaler ADC and NetScaler Gateway contain a buffer overflow vulnerability that allows for sensitive information disclosure when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 8 Nov 2023): Apply mitigations and kill all active and persistent sessions per vendor instructions [https://www.netscaler.com/blog/news/cve-2023-4966-critical-security-update-now-available-for-netscaler-adc-and-netscaler-gateway/] 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