CVE-2023-4966: critical vulnerability in Citrix NetScaler ADC
Unauthenticated sensitive information disclosure
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
Patch now. It under exploitation confirmed by CISA, has an official Brazilian government alert, has a working public exploit and 1 threat group(s) use it.
Brazil's federal government published an alert, recommendation or bulletin that cites this vulnerability.
- CISC Gov.br · 07 Jul 2026Boletim do CISC de Vulnerabilidaderead on gov.br ↗
Groups known to exploit this vulnerability (MITRE ATT&CK attribution).
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.
NetScaler ADC and Gateway servers leak sensitive information without requiring authentication when configured in specific modes. This allows attackers to access confidential data directly over the network.
An unauthenticated remote attacker can exploit improper access controls in NetScaler ADC/Gateway (when configured as VPN, ICA Proxy, CVPN, RDP Proxy, or AAA virtual server) to disclose sensitive information via direct network access, with no pre-conditions beyond network reachability.
The full analysis of this CVE is available in Portuguese →
In the same product, most dangerous first.