Vulnerabilities/Citrix/CVE-2023-4966

CVE-2023-4966: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability

CISA KEV entry · Last checked 30 Oct 2026, 12:10 UTC

Exploitation confirmedRansomware use knownFix: Unknown

CVSS 3.1 · NVD7.5High
EPSS100.0%100th percentile · 29 Oct 2026
CISA KEVListedAdded 18 Oct 2023

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.

Recommended 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.

CISA due date 8 Nov 2023 · CWE-119

Vendor advisory ↗CISA KEV entry ↗

Am I affected?

ProductAffected versionsFixed in
NetScaler ADC14.1 to before 8.50Unknown
NetScaler ADC13.1 to before 49.15Unknown
NetScaler ADC13.0 to before 92.19Unknown
NetScaler ADC13.1-FIPS to before 37.164Unknown
NetScaler ADC12.1-FIPS to before 55.300Unknown
Show 4 more rows
NetScaler ADC12.1-NDcPP to before 55.300Unknown
NetScaler Gateway14.1 to before 8.50Unknown
NetScaler Gateway13.1 to before 49.15Unknown
NetScaler Gateway13.0 to before 92.19Unknown

No source states a fixed version. Check the vendor advisory below.

Before you patch

Restart

See vendor guidance.

Known issues

Check release notes.

Verification

Confirm installed version.

Timeline

  • 18 Oct 2023 · Added to CISA KEV
  • 8 Nov 2023 · CISA due date

References

Sources checked
CISA KEV30 Oct 2026, 12:10 UTC
CVE List v530 Oct 2026, 12:10 UTC
NVD30 Oct 2026, 12:10 UTC
FIRST EPSS30 Oct 2026, 12:11 UTC

Data from CISA, MITRE, NVD and FIRST. Sources and licences.