CVE-2023-4966

CRITICAL9.4

CISA KEV

Published 2023-10-10 · Updated 2026-07-31 · Source secure@citrix.com

Summary

CVE-2023-4966 is a critical-severity (CVSS 9.4) vulnerability in Citrix NetScaler ADC and NetScaler Gateway. CISA added it to the Known Exploited Vulnerabilities catalog on October 18, 2023, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by November 8, 2023. CISA also lists it as known to be used in ransomware campaigns, so it should be prioritised accordingly. Citrix has 27 vulnerabilities in the KEV catalog, 7 of them linked to ransomware.

All 27 known-exploited Citrix vulnerabilities →

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.

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

CWE-119

CISA Known-Exploited Vulnerability

Product: Citrix — NetScaler ADC and NetScaler Gateway

Name: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability

Date added: 2023-10-18 · Due: 2023-11-08

USED IN RANSOMWARE

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.

References

View on NVD

More exploited Citrix vulnerabilities

Most recently added to CISA KEV

CVE-2026-88779
NetScaler — Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability
added 2026-10-04
CVE-2026-88772
NetScaler — Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability
added 2026-09-27
CVE-2026-88771
NetScaler — Citrix NetScaler Improper Input Validation Vulnerability
added 2026-09-27
CVE-2026-19490
NetScaler — Citrix NetScaler Authentication Bypass Using an Alternate Path or Channel Vulnerability
added 2026-09-09
CVE-2026-8452
NetScaler ADC and NetScaler Gateway — Citrix NetScaler ADC and NetScaler Gateway Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability
added 2026-08-26
CVE-2026-3055
NetScaler — Citrix NetScaler Out-of-Bounds Read Vulnerability
added 2026-03-30

View all →

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