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CVE-2023-4966 (GCVE-0-2023-4966)

Vulnerability from cvelistv5 – Published: 2023-10-10 13:12 – Updated: 2026-07-31 03:55
VLAI CISA Shadowserver Previdian
Title
Unauthenticated sensitive information disclosure
Summary
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.
Severity
9.4 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
SSVC
Exploitation: active Automatable: yes Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2023-10-10 00:00 UTC
CWE
  • CWE-119 - Improper Restriction of Operations within the Bounds of a Memory Buffer
Assigner
References
Impacted products
Vendor Product Version CPE status
Citrix NetScaler ADC Affected: 14.1 , < 8.50 (patch)
Affected: 13.1 , < 49.15 (patch)
Affected: 13.0 , < 92.19 (patch)
Affected: 13.1-FIPS , < 37.164 (patch)
Affected: 12.1-FIPS , < 55.300 (patch)
Affected: 12.1-NDcPP , < 55.300 (patch)
guessed Create a notification for this product.
Citrix NetScaler Gateway Affected: 14.1 , < 8.50 (patch)
Affected: 13.1 , < 49.15 (patch)
Affected: 13.0 , < 92.19 (patch)
guessed Create a notification for this product.
Date Public
2023-10-10 12:33
CISA
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: a7d4f808-e166-454b-97a6-902803fe827b

Vulnerability ID: CVE-2023-4966

Status: Confirmed

Status Updated: 2023-10-18 00:00 UTC

Exploited: Yes

Timestamps
First Seen: 2023-10-18
Asserted: 2023-10-18
Scope
Notes: KEV entry: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability | Affected: Citrix / NetScaler ADC and NetScaler Gateway | Description: 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. | 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. | Due date: 2023-11-08 | Known ransomware campaign use (KEV): Known | Notes (KEV): https://www.netscaler.com/blog/news/cve-2023-4966-critical-security-update-now-available-for-netscaler-adc-and-netscaler-gateway/, https://support.citrix.com/article/CTX579459/netscaler-adc-and-netscaler-gateway-security-bulletin-for-cve20234966-and-cve20234967 ; https://nvd.nist.gov/vuln/detail/CVE-2023-4966
Evidence

Type: Vendor Report

Signal: Successful Exploitation

Confidence: 80%

Source: cisa-kev

Details
Cwes CWE-119
Feed CISA Known Exploited Vulnerabilities Catalog
Product NetScaler ADC and NetScaler Gateway
Due Date 2023-11-08
Date Added 2023-10-18
Vendorproject Citrix
Vulnerabilityname Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability
Knownransomwarecampaignuse Known
References
Created: 2026-02-02 12:26 UTC | Updated: 2026-02-06 07:17 UTC
Shadowserver
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: c62cef39-0605-4e25-9aa7-20538a7fd9d4

Vulnerability ID: CVE-2023-4966

Status: Confirmed

Status Updated: 2026-07-19 00:00 UTC

Exploited: Yes

Characteristics
Severity: 75.0
Timestamps
First Seen: 2023-10-25
Asserted: 2023-10-25
Last Seen: 2026-07-19
Scope
Asset Exposure: ['internet-facing']
Notes: Affected: Citrix / Citrix ADC and Citrix Gateway | Class: app-delivery-controller | Severity: High (CVSS 7.5) | IoT: no | In CISA KEV: yes | Honeypot connections on 2026-07-19: 9
Evidence

Type: Honeypot

Signal: In The Wild Attempts

Confidence: 70%

Source: shadowserver

Details
1D 2
Iot no
Feed Shadowserver Foundation honeypot/exploited-vulnerabilities
Type http-scan
Class app-delivery-controller
7D Avg 4
Vendor Citrix
30D Avg 6
90D Avg 18
Product Citrix ADC and Citrix Gateway
Cisa Kev yes
Connections 9
Observation Date 2026-07-19
Vulnerability Class CVSS
Vulnerability Score 7.5
Vulnerability Severity High
References
Created: 2026-06-30 09:22 UTC | Updated: 2026-07-21 01:00 UTC
Previdian
Known Exploited Vulnerability - GCVE BCP-07 Compliant
KEV entry ID: ed7e3a4e-4aec-4457-a6f2-40bf9d880848

Vulnerability ID: CVE-2023-4966

Status: Confirmed

Status Updated: 2023-10-18 00:00 UTC

Exploited: Yes

Timestamps
First Seen: 2023-10-18
Asserted: 2023-10-18
Scope
Notes: KEVIntel entry: Unauthenticated sensitive information disclosure | Affected: Citrix / NetScaler ADC, NetScaler Gateway | CVSS: 9.4 (CRITICAL) | EPSS: 0.99999 | Used in malware: yes | Not yet in CISA KEV: False
Evidence

Type: Public Report

Signal: Confirmed Compromise

Confidence: 70%

Source: kevintel

Details
Feed KEVIntel (kevintel.com)
Title Unauthenticated sensitive information disclosure
Vendor Citrix
Product NetScaler ADC, NetScaler Gateway
Added Date 2023-10-18T00:00:00.000Z
Cvss Score 9.4
Epss Score 0.99999
Cvss Severity CRITICAL
Epss Percentile 0.99993
Used In Malware yes
Ahead Of Cisa Kev None
Not Yet In Cisa Kev False
References
Created: 2026-06-23 14:05 UTC | Updated: 2026-07-10 06:14 UTC
Show details on NVD website
To clipboard 

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Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.