CVE-2023-4966 | Unauthenticated sensitive information disclosure

Exp

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.

Published: 2023-10-10 Last update: 2025-10-24 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-4966 is rated Critical Active Threat (97.6/100): CVSS Critical severity, with high exploitation likelihood (EPSS 94.35%, 100th percentile). CISA KEV confirms active exploitation (added 2023-10-18) affecting Citrix / NetScaler ADC and NetScaler Gateway. a weakness (CWE-119) Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2023-4966

Name: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability · CISA KEV detail

Exploit added: 2023-10-18

Action due: 2023-11-08

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.

Exploit prediction scoring system (EPSS) score for CVE-2023-4966

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-25 94.35% 94.35% -0.00%
2 2026-05-24 94.35% 94.35% +0.00%
3 2026-03-24 — 94.35% —

Full EPSS history (42 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-4966

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.4 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 5.5 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2023-4966

Affected software / configurations for CVE-2023-4966

Vendor Product Version Raw CPE
citrix netscaler_application_delivery_controller >= 12.1, < 12.1-55.300 cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:fips:*:*:*
citrix netscaler_application_delivery_controller >= 12.1, < 12.1-55.300 cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:ndcpp:*:*:*
citrix netscaler_application_delivery_controller >= 13.0, < 13.0-92.19 cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:-:*:*:*
citrix netscaler_application_delivery_controller >= 13.1, < 13.1-37.164 cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:fips:*:*:*
citrix netscaler_application_delivery_controller >= 13.1, < 13.1-49.15 cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:-:*:*:*
citrix netscaler_application_delivery_controller >= 14.1, < 14.1-8.50 cpe:2.3:a:citrix:netscaler_application_delivery_controller:*:*:*:*:-:*:*:*
citrix netscaler_gateway >= 13.0, < 13.0-92.19 cpe:2.3:a:citrix:netscaler_gateway:*:*:*:*:*:*:*:*
citrix netscaler_gateway >= 13.1, < 13.1-49.15 cpe:2.3:a:citrix:netscaler_gateway:*:*:*:*:*:*:*:*
citrix netscaler_gateway >= 14.1, < 14.1-8.50 cpe:2.3:a:citrix:netscaler_gateway:*:*:*:*:*:*:*:*

References for CVE-2023-4966

cvelogic Threat Intelligence