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

Reference page built from the source records below, each shown as its source publishes it. Dataset version ref-4fbc78945fe9, updated 2026-11-02T23:39:54.475Z.

CISA Known Exploited Vulnerabilities

Name
Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability
Vendor
Citrix
Product
NetScaler ADC and NetScaler Gateway
Added to the catalog
2023-10-18
Due date for US federal agencies
2023-11-08
Weaknesses
CWE-119
Catalog version
2026.10.30

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 (CISA)

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.

Ransomware use: CISA marks this vulnerability as known to be used in ransomware campaigns. CISA does not say which group used it.

Links in CISA's notes

Read on 2026-11-02T23:39:54.475Z under licence cisa-kev-cc0@b0067899 from https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

NVD analysis

Status
Analyzed
Published
2023-10-10T14:15:10.977
Last modified
2026-07-31T04:16:44.230
Weaknesses
CWE-119, NVD-CWE-noinfo

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.

MetricScoreSeverityVectorScored by
CVSS 3.19.4CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L[email protected] (Secondary)
CVSS 3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N[email protected] (Primary)

References

This product uses the NVD API but is not endorsed or certified by the NVD.

Read on 2026-11-02T23:42:08.214Z under licence nvd-api-terms-of-use@ff2a5288 from https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2023-4966

CVE record

Title (CNA)
Unauthenticated sensitive information disclosure
Assigner
Citrix
State
PUBLISHED
Published
2023-10-10T13:12:17.644Z
Updated
2026-07-31T03:55:28.627Z
Problem types
CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

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.

References

Read on 2026-11-03T02:05:06.364Z under licence cve-terms-of-use@81bfa2f3 from https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2023/4xxx/CVE-2023-4966.json

Detection rules (SigmaHQ)

SigmaHQ rules whose own tags name this CVE. Each rule page shows the rule as its author published it.

Defensive techniques (MITRE D3FEND)

D3FEND maps these defensive techniques to the weakness (CWE) that NVD lists for this CVE, through the digital artifacts the weakness affects. D3FEND does not say they stop this vulnerability.

CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer

D3FEND ontology version 1.6.0.

Read on 2026-11-02T23:54:38.936Z under licence d3fend-terms-of-use@f98cbc7e from https://d3fend.mitre.org/api/weakness/cwe/CWE-119.json

MITRE D3FEND™ knowledge graph. © 2025 The MITRE Corporation.
"The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use D3FEND for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." Terms: https://d3fend.mitre.org/tou/

Sources and licences

  • CISA

    Source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30, CC0 1.0. Use of this data does not imply endorsement by CISA or DHS.

    CC0 1.0 Universal

  • National Vulnerability Database (NIST)

    This product uses the NVD API but is not endorsed or certified by the NVD.

    NVD API Terms of Use (NIST publications in the public domain, 17 U.S.C. 105)

  • CVE Program, The MITRE Corporation

    Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation. CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy.

    CVE Program Terms of Use ("CVE Usage" licence)

  • SigmaHQ

    "CVE-2023-4966 Potential Exploitation Attempt - Citrix ADC Sensitive Information Disclosure - Webserver" by Nasreddine Bencherchali (Nextron Systems), Michael Haag (STRT) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2023/Exploits/CVE-2023-4966/web_exploit_cve_2023_4966_citrix_sensitive_information_disclosure_exploit.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

  • SigmaHQ

    "CVE-2023-4966 Exploitation Attempt - Citrix ADC Sensitive Information Disclosure - Webserver" by Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2023/Exploits/CVE-2023-4966/web_exploit_cve_2023_4966_citrix_sensitive_information_disclosure_exploit_attempt.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

  • SigmaHQ

    "CVE-2023-4966 Exploitation Attempt - Citrix ADC Sensitive Information Disclosure - Proxy" by Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2023/Exploits/CVE-2023-4966/proxy_exploit_cve_2023_4966_citrix_sensitive_information_disclosure_exploit.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

  • SigmaHQ

    "CVE-2023-4966 Potential Exploitation Attempt - Citrix ADC Sensitive Information Disclosure - Proxy" by Nasreddine Bencherchali (Nextron Systems), Michael Haag (STRT) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2023/Exploits/CVE-2023-4966/proxy_exploit_cve_2023_4966_citrix_sensitive_information_disclosure_exploit_attempt.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

  • MITRE D3FEND

    MITRE D3FEND™ knowledge graph. © 2025 The MITRE Corporation.
    "The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use D3FEND for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." Terms: https://d3fend.mitre.org/tou/

    MITRE D3FEND Terms of Use (site + knowledge graph); source repo MIT

Cite this page

Dragons Eye Ransomware Tracker, "CVE-2023-4966: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability",
entity page, dataset version ref-4fbc78945fe9, updated 2026-11-02T23:39:54.475Z,
https://ransomware-tracker.com/cve/CVE-2023-4966 (accessed 2026-11-03).
Underlying source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30.
Underlying source: National Vulnerability Database (NIST), CVE API 2.0, record last modified 2026-07-31T04:16:44.230.
Underlying source: CVE List (CVE Program, The MITRE Corporation), record updated 2026-07-31T03:55:28.627Z.
Underlying source: SigmaHQ rule 87c83d8e-5390-44ce-aa4a-d3b37e54d0a0, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.
Underlying source: SigmaHQ rule a4e068b5-e27c-4f21-85b3-e69e5a4f7ce1, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.
Underlying source: SigmaHQ rule aee7681f-b53d-4594-a9de-ac51e6ad3362, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.
Underlying source: SigmaHQ rule ff349b81-617f-4af4-924f-dbe8ea9bab41, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.
Underlying source: MITRE D3FEND, ontology version 1.6.0.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.

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