ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2023-4966

Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability

Published Oct 10, 2023 · catalog updated Jul 30, 2026 · Citrix NetScaler ADC and NetScaler Gateway

Patch now

CVE-2023-4966 is in the CISA known-exploited catalog, due Nov 8, 2023. Confirm Citrix NetScaler ADC and NetScaler Gateway against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
Severity
High7.5
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
100.00%
Remediation
Remediation guidance
Affected products
cpe citrix/netscaler application delivery controller · cpe citrix/netscaler gateway · vendor Citrix NetScaler ADC and NetScaler Gateway

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. VulnCheck canary evidence. Initial-access exploit intelligence.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe citrix/netscaler application delivery controllerversion unspecified
  • cpe citrix/netscaler gatewayversion unspecified
  • vendor Citrix NetScaler ADC and NetScaler Gatewayversion unspecified

How to fix CVE-2023-4966

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2023-4966 is in the CISA known-exploited catalog, due Nov 8, 2023. Confirm Citrix NetScaler ADC and NetScaler Gateway against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. 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.

What should an analyst verify?

CWE-119: Buffer Overflow. EPSS 100.00%. The CISA KEV listing is the exploitation evidence. A public exploit reference is linked in Sources. That is not the same as confirmed exploitation. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 10, 2023 · Catalog

    Detected

    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.

  2. Oct 18, 2023 · CISA KEV

    Known exploited

    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.

  3. Nov 8, 2023 · CISA KEV

    Remediation due

    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.

  4. Jul 30, 2026 · Catalog

    Updated

    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.

Sources

  • CISA KEVConfirmed exploitationCVE-2023-4966

    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.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2023-4966

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2023-4966

    30-day exploitation probability 100.0%

    first.org
  • Metasploit ModulesPublic exploit moduleauxiliary_scanner/http/citrix_bleed_cve_2023_4966

    Public module reference (normal). Module source is not copied into this catalog.

    rapid7.com
  • NIST NVDVulnerability recordCVE-2023-4966

    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.

    nvd.nist.gov
  • Packet Storm SecurityCited referencehttp://packetstormsecurity.com/files/175323/Citrix-Bleed-Session-Token-Leakage-Proof-Of-Concept.html

    Packet Storm link already published on the finding.

    packetstormsecurity.com
  • VulnCheck KEVConfirmed exploitationCVE-2023-4966

    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.

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.