How severe is CVE-2023-4966?

CVE-2023-4966 has a CVSS 3.x base score of 9.4, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability low.

Is CVE-2023-4966 being actively exploited?

Yes. CVE-2023-4966 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2023-10-18, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2023-4966?

CVE-2023-4966 primarily affects Citrix Netscaler Application Delivery Controller. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-4966?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2023-4966 have an EU (EUVD) identifier?

Yes. CVE-2023-4966 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-54802. It is also flagged as exploited in the EUVD (since 2023-10-18).

When was CVE-2023-4966 published?

CVE-2023-4966 was published on 2023-10-10 and last updated on 2026-07-31.

CVE-2023-4966

CVE-2023-4966 is a critical-severity vulnerability in Citrix Netscaler Application Delivery Controller with a CVSS 3.x base score of 9.4. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2023-10-18). The underlying weakness is classified as CWE-119.

Key facts

Severity: Critical (CVSS 3.x base score 9.4)
EPSS exploit prediction: 100% (100th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2023-10-18)
EU (EUVD) id: EUVD-2023-54802
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2023-10-18)
Weakness: CWE-119
Affected product: Citrix Netscaler Application Delivery Controller
Published: 2023-10-10
Last modified: 2026-07-31

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.

Frequently asked questions

What is CVE-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.
How severe is CVE-2023-4966?: CVE-2023-4966 has a CVSS 3.x base score of 9.4, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability low.
Is CVE-2023-4966 being actively exploited?: Yes. CVE-2023-4966 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2023-10-18, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2023-4966?: CVE-2023-4966 primarily affects Citrix Netscaler Application Delivery Controller. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-4966?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2023-4966 have an EU (EUVD) identifier?: Yes. CVE-2023-4966 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-54802. It is also flagged as exploited in the EUVD (since 2023-10-18).
When was CVE-2023-4966 published?: CVE-2023-4966 was published on 2023-10-10 and last updated on 2026-07-31.

References

Affected products (4)

cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:fips:*:*:*
cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:ndcpp:*:*:*
cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:-:*:*:*
cpe:2.3:a:citrix:netscaler_gateway:*:*:*:*:*:*:*:*

More vulnerabilities in Citrix Netscaler Application Delivery Controller

CVE-2014-2882 — Critical (CVSS 10.0): Unspecified vulnerability in the management GUI in Citrix NetScaler Application Delivery Controller (ADC) and NetScaler…
CVE-2014-2881 — Critical (CVSS 10.0): Unspecified vulnerability in the Diffie-Hellman key agreement implementation in the management GUI Java applet in…
CVE-2026-8655 — Critical (CVSS 9.8): Multiple Memory overflow vulnerabilities in NetScaler ADC and NetScaler Gateway leading to unpredictable or erroneous…
CVE-2026-8452 — Critical (CVSS 9.8): Memory overflow vulnerability NetScaler ADC and NetScaler Gateway leading to unpredictable or erroneous behavior and…
CVE-2026-3055 — Critical (CVSS 9.8): Insufficient input validation in NetScaler ADC and NetScaler Gateway when configured as a SAML IDP leading…
CVE-2025-7776 — Critical (CVSS 9.8): Memory overflow vulnerability leading to unpredictable or erroneous behavior and Denial of Service in NetScaler ADC…

All CVEs affecting Citrix Netscaler Application Delivery Controller →

Other CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) vulnerabilities

CVE-2026-77946 — Critical (CVSS 10.0): A vulnerability was determined in TRENDnet TEW-821DAP 2.2.01b05. Affected by this vulnerability is the function…
CVE-2026-76008 — Critical (CVSS 10.0): A flaw has been found in Comfast CF-N1-S 2.6.0.1. This affects the function get_para_from_uri of the file…
CVE-2026-75784 — Critical (CVSS 10.0): A vulnerability was detected in TRENDnet TEW-WLC100 1v2.07b01. Affected by this issue is the function FUN_0040da4c of…
CVE-2026-74843 — Critical (CVSS 10.0): A vulnerability was determined in Wavlink WN531P3 and WN535M1 V250922. Affected by this vulnerability is the function…
CVE-2026-16367 — Critical (CVSS 10.0): Sandbox escape due to invalid pointer in the Disability Access APIs component. This vulnerability was fixed in Firefox…
CVE-2026-2778 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability was fixed in…

Browse all CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) vulnerabilities →