CVE-2023-4966

What is affected

Vendor	Citrix
Product	NetScaler ADC and NetScaler Gateway
Weakness	CWE-119

The vulnerability

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.

Required action

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.

US federal civilian agencies were required to act by 8 November 2023 under BOD 22-01. The deadline is a compliance date, not a measure of severity — it says nothing about how dangerous the flaw is to anyone else.

Ransomware

CISA records this vulnerability as having been used in ransomware campaigns. That is a confirmed observation, not an assessment of likelihood.

Where this comes from

Every field on this page is taken from the CISA Known Exploited Vulnerabilities catalog, last synced 11 Nov 2026, 21:30. Nothing here is our own assessment. For the technical scoring, see the NVD record below.

NVD record ↗ CVE.org record ↗